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Al lami Z, Kurtca M, Atique MU, Opekun AR, Siam MS, Jalal PK, Najafi B, Devaraj S, Mindikoglu AL. Dawn-to-dusk dry fasting decreases circulating inflammatory cytokines in subjects with increased body mass index. Metabol Open 2024; 21:100274. [PMID: 38455231 PMCID: PMC10918425 DOI: 10.1016/j.metop.2024.100274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 02/04/2024] [Accepted: 02/06/2024] [Indexed: 03/09/2024] Open
Abstract
Background The circadian rhythm involves numerous metabolic processes, including sleep/awakening, body temperature regulation, hormone secretion, hepatic function, cellular plasticity, and cytokine release (inflammation), that appear to have a dynamic relationship with all the processes above. Studies have linked various cytokines to the chronic state of low-grade inflammation and oxidative stress in obesity. Dawn-to-dusk dry fasting (DDDF) could alleviate the adverse effects of obesity by decreasing inflammation. This study examined the effects of DDDF on circulating inflammatory cytokines in subjects with increased body mass index (BMI). Methods The current observational prospective study included adult subjects with a BMI equal to or greater than 25 kg/m2 who practiced the annual religious 30-day DDDF. Individuals with significant underlying medical conditions were excluded to limit confounding factors. All subjects were evaluated within two weeks before 30-day DDDF, within the fourth week of 30-day DDDF, and within two weeks after 30-day DDDF. Multiple cytokines and clinical health indicators were measured at each evaluation. Results Thirteen subjects (10 men and three women) with a mean age of 32.9 years (SD = 9.7 years) and a mean BMI of 32 kg/m2 (SD = 4.6 kg/m2) were included. An overall associated decrease in the levels of multiple cytokines with DDDF was observed. A significant decrease in the mean interleukin 1 beta level was observed within the fourth week of 30-day DDDF (P = 0.045), which persisted even after the fasting period (P = 0.024). There was also a significant decrease in the mean levels of interleukin 15 (IL-15) (P = 0.014), interleukin 1 receptor antagonist (P = 0.041), macrophage-derived chemokine (MDC) (P = 0.013), and monokine induced by interferon gamma/chemokine (C-X-C motif) ligand 9 (P = 0.027) within the fourth week of 30-day DDDF and in the mean levels of fibroblast growth factor 2 (P = 0.010), interleukin 12 p40 subunit (P = 0.038), interleukin 22 (P = 0.025) and tumor necrosis factor alpha (P = 0.046) within two weeks after 30-DDDF. In terms of anthropometric parameters, there was a decrease in mean body weight (P = 0.032), BMI (P = 0.028), and hip circumference (P = 0.007) within the fourth week of 30-day DDDF and a decrease in mean weight (P = 0.026), BMI (P = 0.033) and hip circumference (P = 0.016) within two weeks after 30-day DDDF compared with the levels measured within two weeks before 30-day DDDF. Although there was no significant correlation between changes in weight and changes in circulating inflammatory cytokines, there was a significant positive correlation between changes in waist circumference and changes in specific inflammatory cytokines (e.g., IL-15, MDC, platelet-derived growth factor, soluble CD40L, vascular endothelial growth factor A) within the fourth week of 30-day DDDF and/or two weeks after 30-day DDDF. A significant decrease in mean average resting heart rate within the fourth week of 30-day DDDF was also observed (P = 0.023), and changes between average resting heart rate and changes in interleukin-8 levels within the fourth week of 30-day DDDF compared with baseline levels were positively correlated (r = 0.57, P = 0.042). Conclusion DDDF appears to be a unique and potent treatment to reduce low-grade chronic inflammation caused by obesity and visceral adiposity. Further studies with more extended follow-up periods are warranted to investigate the long-term anti-inflammatory benefits of DDDF in individuals with increased BMI.
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Affiliation(s)
- Zahraa Al lami
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
| | - Miray Kurtca
- Clinical Chemistry and Point of Care Technology, Texas Children's Hospital and Health Centers, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
| | - Moin Uddin Atique
- Interdisciplinary Consortium on Advanced Motion Performance (iCAMP), Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX, USA
| | - Antone R. Opekun
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
- Department of Pediatrics, Division of Gastroenterology, Nutrition and Hepatology, Baylor College of Medicine, Houston, TX, USA
| | - Mohamad S. Siam
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
| | - Prasun K. Jalal
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
- Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, USA
| | - Bijan Najafi
- Interdisciplinary Consortium on Advanced Motion Performance (iCAMP), Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX, USA
| | - Sridevi Devaraj
- Clinical Chemistry and Point of Care Technology, Texas Children's Hospital and Health Centers, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
| | - Ayse L. Mindikoglu
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
- Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, USA
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Hashimoto S, Endo T, Honma S, Yamanaka Y, Honma KI. Two oscillatory components detected by forced splitting of the sleep-wake cycle in humans. Am J Physiol Regul Integr Comp Physiol 2024; 326:R19-R28. [PMID: 37867474 DOI: 10.1152/ajpregu.00094.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/13/2023] [Accepted: 10/16/2023] [Indexed: 10/24/2023]
Abstract
The sleep-wake cycle of human subjects was artificially split into two episodes by imposing an 8-h light and 4-h dark cycle (LD 8:4) twice a day for 7 days, which was followed by a 3-day free-running session. Sleep was permitted only in the dark period. The subjects in the ordinary group were exposed to ordinary light (ca. 500 lx) in the 8-h light period, and those in the bright light group to bright (ca. 5,000 lx) and ordinary light alternatively with bright light after the first dark period (2400-400). Split sleeps persisted in the free-running session with the major episode around the first dark period and the minor episode around the second dark period. By contrast, circadian melatonin rhythm in the free-running session significantly phase delayed in the ordinary light group, but phase advanced in the bright light group, keeping the melatonin rhythm unsplit. The length of nocturnal melatonin secretion (NMS) was significantly shortened in the bright light group. Interestingly, the falling phase of NMS advanced significantly further than the rising phase. Such a difference was not detected in the ordinary light group. Similar differences were observed in the body temperature rhythm. These findings indicated oscillatory mechanisms underlying split sleeps distinct from the circadian pacemaker and suggested an involvement of different circadian oscillators in the rising and falling phases of NMS, which is consistent with the dual oscillator model proposed for the circadian system of nocturnal rodents.NEW & NOTEWORTHY The present study demonstrated that human sleep was separated into two essentially identical components, which persisted under constant conditions, suggesting circadian oscillator underlying split-sleep episodes. The study also indicated differential light sensitivities in the rising and falling phases of circadian melatonin rhythm, indicating the involvement of two different oscillators. These results consisted of the evening and morning dual-oscillator hypothesis for the circadian pacemaker and the hierarchical model for the pacemaker and sleep-wake cycle.
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Affiliation(s)
- Satoko Hashimoto
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Takuro Endo
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Sato Honma
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Yujiro Yamanaka
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Ken-Ichi Honma
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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3
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Hashimoto S, Endo T, Honma S, Yamanaka Y, Honma KI. Differential responses to artificial photoperiods of the rising and falling phases of human melatonin rhythm are consistent with a dual oscillator hypothesis. Am J Physiol Regul Integr Comp Physiol 2023; 325:R619-R628. [PMID: 37694335 DOI: 10.1152/ajpregu.00095.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/07/2023] [Accepted: 09/07/2023] [Indexed: 09/12/2023]
Abstract
Circadian rhythms and sleep-wake cycles were measured in volunteers staying singly in temporal isolation unit where they were exposed to artificial short and long light-dark (LD) cycles for 7 days. The long day consisted of 16-h light and 8-h dark (LD 16:8) and the short day consisted of 8-h light and 16-h dark (LD 8:16). During the light period, bright light of approximately 5,000 lux was given from the ceiling and during the dark period there was no illumination. Sleep was monitored by bed sensors, wrist actiwatch, and polysomnography (PSG) on the first and last nights of the schedule. Sleep length was significantly longer under LD 8:16 than under LD 16:8 and the sleep quality estimated by PSG was worse under LD 8:16 than under LD 16:8, which were comparable to natural seasonality in sleep. The circadian rhythm in plasma melatonin was measured in dim light (10 lux) before and after the LD exposures. The nocturnal melatonin secretion (NMS) was significantly longer after LD 8:16 than after LD 16:8 due to differential phase shifts of the rising and falling phases of NMS. After LD 8:16, the falling phase was much advanced than the rising phase, whereas after LD 16:8 the rising phase was much delayed than the falling phase, resulting in the NMS compression. These results indicate that the light sensitivity in terms of phase shifting is different in the two circadian phases, supporting a dual oscillator hypothesis with different phase-response curves for light in the human circadian system.NEW & NOTEWORTHY The present study demonstrated differential light responsiveness of the rising and falling phases of nocturnal melatonin secretion in human subjects exposed to artificial long (LD 16:8) and short days (LD 8:16) and suggested the involvement of different oscillators under these phases. The findings well mimicked the seasonality of the circadian rhythms in nature and consisted with the evening/morning dual oscillator hypothesis proposed originally for nocturnal rodents, providing a new concept for the human circadian system.
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Affiliation(s)
- Satoko Hashimoto
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Takuro Endo
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Sato Honma
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Yujiro Yamanaka
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Ken-Ichi Honma
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Mindikoglu AL, Park J, Opekun AR, Abdulsada MM, Wilhelm ZR, Jalal PK, Devaraj S, Jung SY. Dawn-to-dusk dry fasting induces anti-atherosclerotic, anti-inflammatory, and anti-tumorigenic proteome in peripheral blood mononuclear cells in subjects with metabolic syndrome. Metabol Open 2022; 16:100214. [PMID: 36506940 PMCID: PMC9731888 DOI: 10.1016/j.metop.2022.100214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022] Open
Abstract
Background Metabolic syndrome characterized by abdominal obesity, high blood pressure, elevated fasting glucose and triglyceride levels and low high-density lipoprotein cholesterol level is associated with pro-inflammatory state, increased risk for atherosclerosis, and multiple cancers. Our previous results on subjects with metabolic syndrome showed that 4-week dawn-to-dusk (sunset) dry fasting resulted in significant changes in the serum proteome and improvement in several metabolic risk factors. Peripheral blood mononuclear cells (PBMC) proteomics is a powerful tool that can provide mechanistic insights into how dawn-to-dusk dry fasting affects protein expression in metabolic pathways at cellular level. In this study, we determined whether dawn-to-dusk dry fasting would induce favorable changes in PBMC proteome in subjects with metabolic syndrome, similar to the changes induced by dawn-to-dusk dry fasting in the same subjects' serum proteome. Methods We conducted a prospective study on subjects with metabolic syndrome and collected blood specimens before 4-week dawn-to-dusk dry fasting, at the end of 4-week dawn-to-dusk dry fasting, and one week after 4-week dawn-to-dusk dry fasting. We performed untargeted proteomics using nano ultra-high performance liquid chromatography-tandem mass spectrometry to assess the impact of 4-week dawn-to-dusk dry fasting on PBMC proteome. Results There were 14 subjects with metabolic syndrome with a mean age of 59 who fasted from dawn to dusk (strict dry fasting without any liquid or food intake) for more than 14 h daily for 29 days. The quantitative proteome analysis showed that apolipoprotein B (APOB) gene protein products (GP) levels were downregulated and had the most statistical significance of the observed difference at the end of 4-week dawn-to-dusk dry fasting (P = 0.008) and one week after 4-week dawn-to-dusk dry fasting (P = 0.0004) compared with the levels before 4-week dawn-to-dusk dry fasting. The comparison between GP levels before and at the end of 4-week dawn-to-dusk dry fasting showed an alteration in the expression of genes associated with lipid and atherosclerosis pathway (P = 6.014e-4) and C-type lectin receptor signaling pathway (P = 1.064e-5). The genes that were differentially expressed in the lipid and atherosclerosis pathway were APOB (P = 0.008), CD36 (P = 0.040), CALM1, CALM2, CALM3 (P = 0.015), and HSPA8 (P = 0.047). One of the differentially expressed genes in the C-type lectin receptor signaling pathway was lymphocyte-specific protein 1 (LSP1), which showed an average of 19-fold increase at the end of 4-week dawn-to-dusk dry fasting compared with the GP levels before fasting (P = 0.004). Several GPs associated with tumor-suppressor effect (TUBB4B, LSP1, ACTR3B) were upregulated, and GPs associated with tumor-promoter effect (CD36, CALM1, CALM2, CALM3, FLOT2, PPIF) were downregulated at the end of 4-week dawn-to-dusk dry fasting or one week after 4-week dawn-to-dusk dry fasting compared with the GP levels before 4-week dawn-to-dusk dry fasting. Conclusion Based on our results, we conclude that in subjects with metabolic syndrome, 4-week dawn-to-dusk dry fasting induced anti-atherosclerotic, anti-inflammatory, and anti-tumorigenic PMBC proteome. Randomized, controlled clinical trials are needed to further investigate the effect of dawn-to-dusk dry fasting on subjects with chronic metabolic diseases and metabolic syndrome-induced cancers.
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Affiliation(s)
- Ayse L. Mindikoglu
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA,Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, USA,Corresponding author. Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA.
| | - Jihwan Park
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Antone R. Opekun
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA,Department of Pediatrics, Division of Gastroenterology, Nutrition and Hepatology, Baylor College of Medicine, Houston, TX, USA
| | - Mustafa M. Abdulsada
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
| | - Zoe R. Wilhelm
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
| | - Prasun K. Jalal
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA,Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, USA
| | - Sridevi Devaraj
- Clinical Chemistry and Point of Care Technology, Texas Children's Hospital, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
| | - Sung Yun Jung
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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Qian J, Morris CJ, Phillips AJK, Li P, Rahman SA, Wang W, Hu K, Arendt J, Czeisler CA, Scheer FAJL. Unanticipated daytime melatonin secretion on a simulated night shift schedule generates a distinctive 24-h melatonin rhythm with antiphasic daytime and nighttime peaks. J Pineal Res 2022; 72:e12791. [PMID: 35133678 PMCID: PMC8930611 DOI: 10.1111/jpi.12791] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 11/29/2022]
Abstract
The daily rhythm of plasma melatonin concentrations is typically unimodal, with one broad peak during the circadian night and near-undetectable levels during the circadian day. Light at night acutely suppresses melatonin secretion and phase shifts its endogenous circadian rhythm. In contrast, exposure to darkness during the circadian day has not generally been reported to increase circulating melatonin concentrations acutely. Here, in a highly-controlled simulated night shift protocol with 12-h inverted behavioral/environmental cycles, we unexpectedly found that circulating melatonin levels were significantly increased during daytime sleep (p < .0001). This resulted in a secondary melatonin peak during the circadian day in addition to the primary peak during the circadian night, when sleep occurred during the circadian day following an overnight shift. This distinctive diurnal melatonin rhythm with antiphasic peaks could not be readily anticipated from the behavioral/environmental factors in the protocol (e.g., light exposure, posture, diet, activity) or from current mathematical model simulations of circadian pacemaker output. The observation, therefore, challenges our current understanding of underlying physiological mechanisms that regulate melatonin secretion. Interestingly, the increase in melatonin concentration observed during daytime sleep was positively correlated with the change in timing of melatonin nighttime peak (p = .002), but not with the degree of light-induced melatonin suppression during nighttime wakefulness (p = .92). Both the increase in daytime melatonin concentrations and the change in the timing of the nighttime peak became larger after repeated exposure to simulated night shifts (p = .002 and p = .006, respectively). Furthermore, we found that melatonin secretion during daytime sleep was positively associated with an increase in 24-h glucose and insulin levels during the night shift protocol (p = .014 and p = .027, respectively). Future studies are needed to elucidate the key factor(s) driving the unexpected daytime melatonin secretion and the melatonin rhythm with antiphasic peaks during shifted sleep/wake schedules, the underlying mechanisms of their relationship with glucose metabolism, and the relevance for diabetes risk among shift workers.
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Affiliation(s)
- Jingyi Qian
- Medical Chronobiology Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Christopher J Morris
- Medical Chronobiology Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Andrew JK Phillips
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Peng Li
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
| | - Shadab A Rahman
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Wei Wang
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Kun Hu
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
| | - Josephine Arendt
- School of Biological Sciences, University of Surrey, Guildford, Surrey, United Kingdom
| | - Charles A Czeisler
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Frank AJL Scheer
- Medical Chronobiology Program, Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep and Circadian Disorders, Depts. Of Medicine and Neurology, Brigham and Women’s Hospital, Boston, MA 02115, United States
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, United States
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Klerman EB, Barbato G, Czeisler CA, Wehr TA. Can People Sleep Too Much? Effects of Extended Sleep Opportunity on Sleep Duration and Timing. Front Physiol 2022; 12:792942. [PMID: 35002775 PMCID: PMC8727775 DOI: 10.3389/fphys.2021.792942] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 11/15/2021] [Indexed: 11/18/2022] Open
Abstract
Many people are concerned about whether they are getting “enough” sleep, and if they can “sleep too much.” These concerns can be approached scientifically using experiments probing long-term (i.e., multi-night) sleep homeostatic processes, since homeostatic processes move the system toward its physiological setpoint (i.e., between “not enough” and “too much”). We analyzed sleep data from two human studies with sleep opportunities much longer than people usually stay in bed (i.e., conditions in which sleep homeostatic responses could be documented): sleep opportunities were 14–16 h per day for 3–28 days. Across the nights of the extended sleep opportunities, total sleep duration, Rapid Eye Movement (REM) sleep duration and non-REM sleep durations decreased and sleep latency increased. Multiple nights were required to reach approximately steady-state values. These results suggest a multi-day homeostatic sleep process responding to self-selected insufficient sleep duration prior to the study. Once steady state-values were reached, there were large night-to-night variations in total sleep time and other sleep metrics. Our results therefore answer these concerns about sleep amount and are important for understanding the basic physiology of sleep and for two sleep-related topics: (i) the inter-individual and intra-individual variability are relevant to understanding “normal” sleep patterns and for people with insomnia and (ii) the multiple nights of sleep required for recovery from insufficient sleep from self-selected sleep loss is important for public health and other efforts for reducing the adverse effects of sleep loss on multiple areas of physiology.
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Affiliation(s)
- Elizabeth B Klerman
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States.,Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - Giuseppe Barbato
- Department of Psychology, University degli Studi della Campania Luigi Vanvitelli, Campania, Italy
| | - Charles A Czeisler
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States
| | - Thomas A Wehr
- Intramural Research Program, NIMH, Bethesda, MD, United States
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Bhatti SI, Mindikoglu AL. The impact of dawn to sunset fasting on immune system and its clinical significance in Covid-19 pandemic. Metabol Open 2021; 13:100162. [PMID: 34977523 PMCID: PMC8713419 DOI: 10.1016/j.metop.2021.100162] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 12/23/2021] [Accepted: 12/24/2021] [Indexed: 02/06/2023] Open
Abstract
Dawn to sunset fasting, a type of intermittent fasting commonly practiced in the month of Ramadan, requires fasting from dawn to sunset without food or liquid intake. Dawn and dusk are two transition time zones of the day that play a critical role in the human circadian rhythm. Practicing dawn to sunset fasting requires the alignment of mealtimes and wake-sleep times with the human biological dawn and dusk. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impairs immune cell responses at multiple levels and leads to severe Coronavirus Disease 2019 (COVID-19). It generates high levels of pro-inflammatory cytokines and chemokines, also known as a cytokine storm, leads to mitochondrial dysfunction and generation of excessive amounts of mitochondrial reactive oxygen species, downregulates autophagy to escape detection for unchecked replication, and alters gut microbiome composition. Severe cases of COVID-19 have been associated with several comorbidities that impair immune responses (e.g., obesity, diabetes, malignancy) and blood laboratory abnormalities (e.g., elevated procalcitonin, C-reactive protein, interleukin-6 (IL-6), leukocytosis, lymphopenia). Several studies of dawn to sunset fasting showed anti-inflammatory effect by suppressing several pro-inflammatory cytokines, reducing oxidative stress, inducing a proteome response associated with increased autophagy, remodeling the gut microbiome, and improving the components of metabolic syndrome (e.g., obesity, blood glucose levels, blood pressure, lipids). In conclusion, dawn to sunset fasting has the potential to optimize the immune system function against SARS-CoV-2 during the COVID-19 pandemic as it suppresses chronic inflammation and oxidative stress, improves metabolic profile, and remodels the gut microbiome. This review presents scientific literature related to the effects of dawn to sunset fasting on the immune system. Studies are needed to assess and confirm the potential benefits of dawn to sunset fasting against SARS-CoV-2.
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Affiliation(s)
- Sundus I Bhatti
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA.,Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, USA
| | - Ayse L Mindikoglu
- Margaret M. and Albert B. Alkek Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA.,Michael E. DeBakey Department of Surgery, Division of Abdominal Transplantation, Baylor College of Medicine, Houston, TX, USA
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8
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Moreno JP, Crowley SJ, Alfano CA, Thompson D. Physiological mechanisms underlying children's circannual growth patterns and their contributions to the obesity epidemic in elementary school age children. Obes Rev 2020; 21:e12973. [PMID: 31737994 PMCID: PMC7002188 DOI: 10.1111/obr.12973] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/18/2019] [Accepted: 10/18/2019] [Indexed: 12/20/2022]
Abstract
Several studies since the 1990s have demonstrated that children increase their body mass index at a faster rate during summer months compared with the school year, leading some to conclude that the out-of-school summer environment is responsible. Other studies, however, have suggested that seasonality may play a role in children's height and weight changes across the year. This article reviews evidence for seasonal differences in the rate of children's height and weight gain and proposes potential physiological mechanisms that may explain these seasonal variations.
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Affiliation(s)
- Jennette P Moreno
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Stephanie J Crowley
- Biological Rhythm Research Laboratory, Department of Psychiatry and Behavioral Sciences, Rush University Medical Center, Chicago, Illinois
| | - Candice A Alfano
- Sleep and Anxiety Center of Houston (SACH), Department of Psychology, University of Houston, Houston, Texas
| | - Debbe Thompson
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
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Zubidat AE, Fares B, Fares F, Haim A. Artificial Light at Night of Different Spectral Compositions Differentially Affects Tumor Growth in Mice: Interaction With Melatonin and Epigenetic Pathways. Cancer Control 2019; 25:1073274818812908. [PMID: 30477310 PMCID: PMC6259078 DOI: 10.1177/1073274818812908] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Lighting technology is rapidly advancing toward shorter wavelength illuminations
that offer energy-efficient properties. Along with this advantage, the increased
use of such illuminations also poses some health challenges, particularly breast
cancer progression. Here, we evaluated the effects of artificial light at night
(ALAN) of 4 different spectral compositions (500-595 nm) at 350 Lux on melatonin
suppression by measuring its urine metabolite 6-sulfatoxymelatonin, global DNA
methylation, tumor growth, metastases formation, and urinary corticosterone
levels in 4T1 breast cancer cell-inoculated female BALB/c mice. The results
revealed an inverse dose-dependent relationship between wavelength and melatonin
suppression. Short wavelength increased tumor growth, promoted lung metastases
formation, and advanced DNA hypomethylation, while long wavelength lessened
these effects. Melatonin treatment counteracted these effects and resulted in
reduced cancer burden. The wavelength suppression threshold for
melatonin-induced tumor growth was 500 nm. These results suggest that short
wavelength increases cancer burden by inducing aberrant DNA methylation mediated
by the suppression of melatonin. Additionally, melatonin suppression and global
DNA methylation are suggested as promising biomarkers for early diagnosis and
therapy of breast cancer. Finally, ALAN may manifest other physiological
responses such as stress responses that may challenge the survival fitness of
the animal under natural environments.
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Affiliation(s)
- A E Zubidat
- 1 The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Haifa, Israel
| | - B Fares
- 2 Department of Human Biology, University of Haifa, Haifa, Israel.,3 Department of Molecular Genetics, Carmel Medical Center, Haifa, Israel
| | - F Fares
- 2 Department of Human Biology, University of Haifa, Haifa, Israel.,3 Department of Molecular Genetics, Carmel Medical Center, Haifa, Israel
| | - A Haim
- 1 The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Haifa, Israel
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10
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Moreno JP, Crowley SJ, Alfano CA, Hannay KM, Thompson D, Baranowski T. Potential circadian and circannual rhythm contributions to the obesity epidemic in elementary school age children. Int J Behav Nutr Phys Act 2019; 16:25. [PMID: 30845969 PMCID: PMC6404311 DOI: 10.1186/s12966-019-0784-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/25/2019] [Indexed: 02/06/2023] Open
Abstract
Children gain weight at an accelerated rate during summer, contributing to increases in the prevalence of overweight and obesity in elementary-school children (i.e., approximately 5 to 11 years old in the US). Int J Behav Nutr Phys Act 14:100, 2017 explained these changes with the "Structured Days Hypothesis" suggesting that environmental changes in structure between the school year and the summer months result in behavioral changes that ultimately lead to accelerated weight gain. The present article explores an alternative explanation, the circadian clock, including the effects of circannual changes and social demands (i.e., social timing resulting from societal demands such as school or work schedules), and implications for seasonal patterns of weight gain. We provide a model for understanding the role circadian and circannual rhythms may play in the development of child obesity, a framework for examining the intersection of behavioral and biological causes of obesity, and encouragement for future research into bio-behavioral causes of obesity in children.
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Affiliation(s)
- Jennette P. Moreno
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, 1100 Bates Street, Houston, TX 77030 USA
| | - Stephanie J. Crowley
- Biological Rhythm Research Laboratory, Department of Behavioral Sciences, Rush University Medical Center, Chicago, IL USA
| | - Candice A. Alfano
- Sleep and Anxiety Center of Houston (SACH), Department of Psychology, University of Houston, Houston, TX USA
| | - Kevin M. Hannay
- Department of Mathematics, Schreiner University, Kerrville, TX USA
| | - Debbe Thompson
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, 1100 Bates Street, Houston, TX 77030 USA
| | - Tom Baranowski
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, 1100 Bates Street, Houston, TX 77030 USA
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11
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Responses to Intermittent Light Stimulation Late in the Night Phase Before Dawn. Clocks Sleep 2018; 1:26-41. [PMID: 33089153 PMCID: PMC7509681 DOI: 10.3390/clockssleep1010004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 09/26/2018] [Indexed: 12/04/2022] Open
Abstract
The circadian clock is comprised of two oscillators that independently track sunset (evening) and sunrise (morning), though little is known about how light responses differ in each. Here, we quantified the morning oscillator’s responses to 19 separate pulse trains, collecting observations from over 1300 Drosophila at ZT23. Our results show that the advances in activity onset produced by these protocols depended on the tempo of light administration even when total exposure was conserved across a 15-min window. Moreover, patterns of stimulation previously shown to optimize the evening oscillator’s delay resetting at ZT13 (an hour after dusk) were equally effective for the M oscillator at ZT23 (an hour before dawn), though the morning oscillator was by comparison more photosensitive and could benefit from a greater number of fractionation strategies that better converted light into phase-shifting drive. These data continue to build the case that the reading frames for the pacemaker’s time-of-day estimates at dusk and dawn are not uniform and suggest that the “photologic” for the evening versus morning oscillator’s resetting might be dissociable.
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12
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van der Merwe I, Oosthuizen MK, Ganswindt A, Haim A, Bennett NC. Effects of photophase illuminance on locomotor activity, urine production and urinary 6-sulfatoxymelatonin in nocturnal and diurnal South African rodents. ACTA ACUST UNITED AC 2017; 220:1684-1692. [PMID: 28209805 DOI: 10.1242/jeb.146951] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 02/14/2017] [Indexed: 11/20/2022]
Abstract
Effects of photophase illuminance (1, 10, 100 and 330 lx of white incandescent lighting) on daily rhythms of locomotor activity, urine production and 6-sulfatoxymelatonin (6-SMT; 10 versus 330 lx) were studied in nocturnal Namaqua rock mice (Micaelamys namaquensis) and diurnal four-striped field mice (Rhabdomys pumilio). Micaelamys namaquensis was consistently nocturnal (∼90-94% nocturnal activity), whereas considerable individual variation marked activity profiles in R. pumilio, but with activity mostly pronounced around twilight (∼55-66% diurnal activity). The amplitude of daily activity was distinctly affected by light intensity and this effect was greater in M. namaquensis than in R. pumilio Only M. namaquensis displayed a distinctive daily rhythm of urine production, which correlated with its activity rhythm. Mean daily urine production appeared to be attenuated under dim photophase conditions, particularly in R. pumilio The results suggest that the circadian regulation of locomotor activity and urine production possesses separate sensitivity thresholds to photophase illuminance. Micaelamys namaquensis expressed a significant daily 6-SMT rhythm that peaked during the late night, but the rhythm was attenuated by the brighter photophase cycle (330 lx). Rhabdomys pumilio appeared to express an ultradian 6-SMT rhythm under both lighting regimes with comparable mean daily 6-SMT values, but with different temporal patterns. It is widely known that a natural dark phase which is undisturbed by artificial light is essential for optimal circadian function. Here, we show that light intensity during the photophase also plays a key role in maintaining circadian rhythms in rodents, irrespective of their temporal activity rhythm.
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Affiliation(s)
- Ingrid van der Merwe
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Maria K Oosthuizen
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Andre Ganswindt
- Endocrine Research Laboratory, Department of Anatomy and Physiology, Ondesterpoort, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Abraham Haim
- Israeli Center for Interdisciplinary Studies in Chronobiology, University of Haifa, Haifa 31905, Israel
| | - Nigel C Bennett
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
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13
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Smolensky MH, Sackett-Lundeen LL, Portaluppi F. Nocturnal light pollution and underexposure to daytime sunlight: Complementary mechanisms of circadian disruption and related diseases. Chronobiol Int 2015; 32:1029-48. [PMID: 26374931 DOI: 10.3109/07420528.2015.1072002] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Routine exposure to artificial light at night (ALAN) in work, home, and community settings is linked with increased risk of breast and prostate cancer (BC, PC) in normally sighted women and men, the hypothesized biological rhythm mechanisms being frequent nocturnal melatonin synthesis suppression, circadian time structure (CTS) desynchronization, and sleep/wake cycle disruption with sleep deprivation. ALAN-induced perturbation of the CTS melatonin synchronizer signal is communicated maternally at the very onset of life and after birth via breast or artificial formula feedings. Nighttime use of personal computers, mobile phones, electronic tablets, televisions, and the like--now epidemic in adolescents and adults and highly prevalent in pre-school and school-aged children--is a new source of ALAN. However, ALAN exposure occurs concomitantly with almost complete absence of daytime sunlight, whose blue-violet (446-484 nm λ) spectrum synchronizes the CTS and whose UV-B (290-315 nm λ) spectrum stimulates vitamin D synthesis. Under natural conditions and clear skies, day/night and annual cycles of UV-B irradiation drive corresponding periodicities in vitamin D synthesis and numerous bioprocesses regulated by active metabolites augment and strengthen the biological time structure. Vitamin D insufficiency and deficiency are widespread in children and adults in developed and developing countries as a consequence of inadequate sunlight exposure. Past epidemiologic studies have focused either on exposure to too little daytime UV-B or too much ALAN, respectively, on vitamin D deficiency/insufficiency or melatonin suppression in relation to risk of cancer and other, e.g., psychiatric, hypertensive, cardiac, and vascular, so-called, diseases of civilization. The observed elevated incidence of medical conditions the two are alleged to influence through many complementary bioprocesses of cells, tissues, and organs led us to examine effects of the totality of the artificial light environment in which humans reside today. Never have chronobiologic or epidemiologic investigations comprehensively researched the potentially deleterious consequences of the combination of suppressed vitamin D plus melatonin synthesis due to life in today's man-made artificial light environment, which in our opinion is long overdue.
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Affiliation(s)
- Michael H Smolensky
- a Department of Biomedical Engineering , Cockrell School of Engineering, The University of Texas at Austin , Austin , TX , USA
| | - Linda L Sackett-Lundeen
- b American Association for Clinical Chronobiology and Chronotherapeutics , Roseville , MN , USA , and
| | - Francesco Portaluppi
- c Hypertension Center, S. Anna University Hospital, University of Ferrara , Ferrara , Italy
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14
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Kripke DF, Elliott JA, Welsh DK, Youngstedt SD. Photoperiodic and circadian bifurcation theories of depression and mania. F1000Res 2015; 4:107. [PMID: 26180634 PMCID: PMC4490783 DOI: 10.12688/f1000research.6444.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/05/2015] [Indexed: 12/26/2022] Open
Abstract
Seasonal effects on mood have been observed throughout much of human history. Seasonal changes in animals and plants are largely mediated through the changing photoperiod (i.e., the photophase or duration of daylight). We review that in mammals, daylight specifically regulates SCN (suprachiasmatic nucleus) circadian organization and its control of melatonin secretion. The timing of melatonin secretion interacts with gene transcription in the pituitary pars tuberalis to modulate production of TSH (thyrotropin), hypothalamic T3 (triiodothyronine), and tuberalin peptides which modulate pituitary production of regulatory gonadotropins and other hormones. Pituitary hormones largely mediate seasonal physiologic and behavioral variations. As a result of long winter nights or inadequate illumination, we propose that delayed morning offset of nocturnal melatonin secretion, suppressing pars tuberalis function, could be the main cause for winter depression and even cause depressions at other times of year. Irregularities of circadian sleep timing and thyroid homeostasis contribute to depression. Bright light and sleep restriction are antidepressant and conversely, sometimes trigger mania. We propose that internal desynchronization or bifurcation of SCN circadian rhythms may underlie rapid-cycling manic-depressive disorders and perhaps most mania. Much further research will be needed to add substance to these theories.
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Affiliation(s)
- Daniel F Kripke
- Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, CA, 92093-0603, USA
| | - Jeffrey A Elliott
- Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, CA, 92093-0603, USA
| | - David K Welsh
- Department of Psychiatry and Center for Circadian Biology, University of California, San Diego, CA, 92093-0603, USA
| | - Shawn D Youngstedt
- College of Nursing and Health Innovation, Arizona State University, Phoenix, AZ, 85004-4431, USA
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15
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Raiewski EE, Elliott JA, Evans JA, Glickman GL, Gorman MR. Twice daily melatonin peaks in Siberian but not Syrian hamsters under 24 h light:dark:light:dark cycles. Chronobiol Int 2012; 29:1206-15. [PMID: 23003567 DOI: 10.3109/07420528.2012.719965] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The daily pattern of blood-borne melatonin varies seasonally under the control of a multi-oscillator circadian pacemaker. Here we examine patterns of melatonin secretion and locomotor activity in Siberian and Syrian hamsters entrained to bimodal LDLD8:4:8:4 and LD20:4 lighting schedules that facilitate novel temporal arrangements of component circadian oscillators. Under LDLD, both species robustly bifurcated wheel-running activity in distinct day scotophase (DS) and night scotophase (NS) bouts. Siberian hamsters displayed significant melatonin increases during each scotophase in LDLD, and in the single daily scotophase of LD20:4. The bimodal melatonin secretion pattern persisted in acutely extended 16 h scotophases. Syrian hamsters, in contrast, showed no significant increases in plasma melatonin during either scotophase of LDLD8:4:8:4 or in LD20:4. In this species, detectable levels were observed only when the DS of LDLD was acutely extended to yield 16 h of darkness. Established species differences in the phase lag of nocturnal melatonin secretion relative to activity onset may underlie the above contrast: In non-bifurcated entrainment to 24 h LD cycles, Siberian hamsters show increased melatonin secretion within ≈ 2 h after activity onset, whereas in Syrian hamsters, detectable melatonin secretion phase lags activity onset and the L/D transition by at least 4 h. The present results provide new evidence indicating multi-oscillator regulation of the waveform of melatonin secretion, specifically, the circadian control of the onset, offset and duration of nocturnal secretion.
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Affiliation(s)
- Evan E Raiewski
- Department of Psychology, and Center for Chronobiology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0109, USA.
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16
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Harrison EM, Gorman MR. Changing the waveform of circadian rhythms: considerations for shift-work. Front Neurol 2012; 3:72. [PMID: 22557994 PMCID: PMC3340571 DOI: 10.3389/fneur.2012.00072] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 04/13/2012] [Indexed: 11/24/2022] Open
Abstract
Circadian disruption in shift-work is common and has deleterious effects on health and performance. Current efforts to mitigate these harms reasonably focus on the phase of the circadian pacemaker, which unfortunately in humans, shifts slowly and often incompletely. Temporal reorganization of rhythmic waveform (i.e., the shape of its 24 h oscillation), rather than phase, however, may better match performance demands of shift-workers and can be quickly and feasibly implemented in animals. In fact, a bifurcated pacemaker waveform may permit stable entrainment of a bimodal sleep/wake rhythm promoting alertness in both night and daylight hours. Although bifurcation has yet to be formally assessed in humans, evidence of conserved properties of circadian organization and plasticity predict its occurrence: humans respond to conventional manipulations of waveform (e.g., photoperiodism); behaviorally, the sleep/wake rhythm is adaptable; and finally, the human circadian system likely derives from the same multiple cellular oscillators that permit waveform flexibility in the rodent pacemaker. In short, investigation into untried manipulations of waveform in humans to facilitate adjustment to challenging schedules is justified.
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Affiliation(s)
- Elizabeth M Harrison
- Department of Psychology, Center for Chronobiology, University of California San Diego La Jolla, CA, USA
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17
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Zubidat AE, Nelson RJ, Haim A. Photoentrainment in blind and sighted rodent species: responses to photophase light with different wavelengths. J Exp Biol 2010; 213:4213-22. [DOI: 10.1242/jeb.048629] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
SUMMARY
Our study examined the impact of daylight (photophase) wavelength on the photoentrainment sensitivity of two species with vastly different visual systems. Social voles (Microtus socialis) and ‘blind’ mole rats (Spalax ehrenbergi) were exposed to short-wavelength (479 nm) or long-wavelength (697 nm) light at an intensity of 293 μW cm–2. Rhythms of urine production, urinary 6-sulfatoxymelatonin (6-SMT), urinary metabolites of adrenaline and cortisol, and oxygen consumption (VO2) were used as markers for the sensitivity of the photoentrainment system. Significant 24-h rhythms were detected in all variables for both species under short-wavelength light, whereas ultradian rhythms of 12- or 8-h were detected under long-wavelength light. Wavelength inversely affected 6-SMT levels in M. socialis (negative correlation) and S. ehrenbergi (positive correlation). Increased levels of stress hormone metabolites were detected in M. socialis under the long-wavelength light whereas, in S. ehrenbergi elevated levels were secreted under short-wavelength light. Long-wavelength light increased VO2 in M. socialis and decreased it in S. ehrenbergi; short-wavelength light elicited the opposite effects. Our results indicate that photophase wavelength is an integral light property for modulating photoperiodic responses in mammals, including visually challenged species. Finally, the spectral-induced differential responses between the two species potentially represent adaptive physiological flexibility in species with contrasting visual and habitat challenges.
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Affiliation(s)
- Abed E. Zubidat
- Department of Evolution and Environmental Biology, University of Haifa, Mount Carmel, Haifa 31905, Israel
| | - Randy J. Nelson
- Departments of Neuroscience and Psychology, Ohio State University, Columbus, OH 43210, USA
| | - Abraham Haim
- Department of Evolution and Environmental Biology, University of Haifa, Mount Carmel, Haifa 31905, Israel
- The Israeli Center for Interdisciplinary Research in Chronobiology, University of Haifa, Mount Carmel, Haifa 31905, Israel
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18
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Zubidat AE, Nelson RJ, Haim A. Photosensitivity to different light intensities in blind and sighted rodents. J Exp Biol 2009; 212:3857-64. [DOI: 10.1242/jeb.033969] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Photoperiod is an important cue regulating biological rhythms in mammals, including ‘blind’ subterranean and sighted fossorial rodent species. These species may respond differentially to changes in light quality according to their retinal complexity. The effects of increasing light intensity on daily rhythms of urine excretion and urinary output of 6-sulfatoxymelatonin levels were compared in ‘blind’ mole rats Spalax ehrenbergi and sighted social voles, Microtus socialis. Our results show that the threshold irradiance required to entrain rhythms of voles is three magnitudes greater than that for mole rats. The results suggest that mole rats have an operational photoreceptive pathway with a lower threshold irradiance than voles. Such a low threshold reflects the remarkable capability of this ‘blind’ species to utilize light signals even under challenging light conditions.
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Affiliation(s)
- A. E. Zubidat
- Department of Evolution and Environmental Biology, University of Haifa, Haifa 31905, Israel
| | - R. J. Nelson
- Departments of Psychology and Neuroscience, Ohio State University, Columbus, OH 43210, USA
| | - A. Haim
- Department of Evolution and Environmental Biology, University of Haifa, Haifa 31905, Israel
- Department of Biology, University of Haifa—Oranim, Kiryat Tivon 36006, Israel
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19
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Abstract
Recent refinements in methodology allow chronobiological researchers to answer the following questions: is there circadian misalignment in sleep and mood disturbances, and, if so, is it of the phase-advance or phase-delay type? Measurement of the dim light melatonin onset-to-midsleep interval, or phase-angle difference, in sleep and mood disorders should answer these questions. Although the phase-advance hypothesis of affective disorders was formulated three decades ago, recent studies suggest that many, if not all, mood disturbances have a circadian misalignment component of the phase-delay type, operationally defined as a delay in the dim light melatonin onset relative to the sleep/wake cycle. Phase-delayed disorders can be treated with bright light in the morning and/or low-dose melatonin in the afternoon/evening. Phase-advanced disorders can be treated with bright light in the evening and/or low-dose melatonin in the morning.
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20
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Lewy AJ, Rough JN, Songer JB, Mishra N, Yuhas K, Emens JS. The phase shift hypothesis for the circadian component of winter depression. DIALOGUES IN CLINICAL NEUROSCIENCE 2008. [PMID: 17969866 PMCID: PMC3202495 DOI: 10.31887/dcns.2007.9.3/alewy] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The finding that bright light can suppress melatonin production led to the study of two situations, indeed, models, of light deprivation: totally blind people and winterdepressives. The leading hypothesis for winter depression (seasonal affective disorder, or SAD) is the phase shift hypothesis (PSH). The PSH was recently established in a study in which SAD patients were given low-dose melatonin in the afternoon/evening to cause phase advances, or in the morning to cause phase delays, or placebo. The prototypical phase-delayed patient as well as the smaller subgroup of phase-advanced patients, optimally responded to melatonin given at the correct time. Symptom severity improved as circadian misalignment was corrected. Orcadian misalignment is best measured as the time interval between the dim light melatonin onset (DLMO) and mid-sleep. Using the operational definition of the plasma DLMO as the interpolated time when melatonin levels continuously rise above the threshold of 10 pglmL, the average interval between DLMO and mid-sleep in healthy controls is 6 hours, which is associated with optimal mood in SAD patients.
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Affiliation(s)
- Alfred J Lewy
- Oregon Health & Science University, Department of Psychiatry, Sleep and Mood Disorders Laboratory, Portland, Oregon, USA.
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21
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Van Someren EJW, Nagtegaal E. Improving melatonin circadian phase estimates. Sleep Med 2007; 8:590-601. [PMID: 17493871 DOI: 10.1016/j.sleep.2007.03.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 01/18/2007] [Accepted: 03/02/2007] [Indexed: 10/23/2022]
Abstract
The quality and quantity of sleep is to a large extent determined by whether the sleep period is in alignment with the most favorable circadian time window for sleep. Misalignment results in compromised sleep. In order to determine this circadian time window, the 24-h profile of melatonin secretion is generally considered to provide the most optimal estimate. Melatonin secretion occurs only during the night, and several methods to determine its onset and offset markers have been proposed. In spite of the usefulness of determining circadian phase estimates from melatonin, its feasibility is somewhat restricted because the required number of repeated measurements comes at a high cost for compliance and laboratory assays. In addition, the complexity of some of the previously proposed methods to analyze data and obtain phase estimates may require a statistician. We here propose a set of novel functions to better describe the typical melatonin profile, which usually has a rather fixed baseline level during the day, has differences in the steepness of its rising and falling limbs, and may have a nocturnal plateau or even two peaks instead of one during the night. The functions can easily be fitted, even to incomplete or noisy melatonin data, with the most common statistical software packages, and the resulting parameters give direct information on the mentioned characteristics, which provide important additions to complete the usual restricted information on phase and amplitude. We show that the proposed curves fit better than single- to three-harmonic cosine curves to the typical melatonin profiles of both healthy subjects (n=13) and subjects diagnosed with Delayed Sleep Phase Syndrome (DSPS, n=27), Disorders of Initiating and Maintaining Sleep (DIMS, n=9), or sleep complaints not otherwise specified (n=7). Of note, because the functions provide a parsimonious description of the melatonin profile, phase estimates derived from them are more reliable (i.e., robust for noise and data loss). We illustrate that phase estimates deviate on average only by about 10 min in case of the loss of some of the data points and in case of the addition of noise. Finally, we introduce a sparse-sampling schedule tailored to capture the most important aspects of the melatonin curve. It is shown that such schedule - reducing the number of samples by more than 50% - in combination with the proposed functions results in reliable melatonin onset phase estimates, deviating only about 10 min from estimates based on 24 samples. The proposed methods strongly contribute to the feasibility, in terms of both cost and analysis availability, for researchers and clinicians to include the most reliable marker of the circadian timing system in their diagnosis and treatment evaluations.
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Affiliation(s)
- Eus J W Van Someren
- Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands.
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22
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Takasu NN, Hashimoto S, Yamanaka Y, Tanahashi Y, Yamazaki A, Honma S, Honma KI. Repeated exposures to daytime bright light increase nocturnal melatonin rise and maintain circadian phase in young subjects under fixed sleep schedule. Am J Physiol Regul Integr Comp Physiol 2006; 291:R1799-807. [PMID: 16840653 DOI: 10.1152/ajpregu.00211.2006] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Effects of two different light intensities during daytime were examined on human circadian rhythms in plasma melatonin, core body temperature, and wrist activity under a fixed sleep schedule. Sleep qualities as indicated by polysomnography and subjective sleepiness were also measured. In the first week, under dim light conditions ( approximately 10 lx), the onset and peak of nocturnal melatonin rise were significantly delayed, whereas the end of melatonin rise was not changed. The peak level of melatonin rise was not affected. As a result, the width of nocturnal melatonin rise was significantly shortened. In the second week, under bright light conditions ( approximately 5,000 lx), the phases of nocturnal melatonin rise were not changed further, but the peak level was significantly increased. Core body temperature at the initial sleep phase was progressively elevated during the course of dim light exposure and reached the maximum level at the first night of bright light conditions. Subjective sleepiness gradually declined in the course of dim light exposure and reached the minimum level at the first day of bright light. These findings indicate that repeated exposures to daytime bright light are effective in controlling the circadian phase and increasing the peak level of nocturnal melatonin rise in plasma and suggest a close correlation between phase-delay shifts of the onset of nocturnal melatonin rise or body temperature rhythm and daytime sleepiness.
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Affiliation(s)
- Nana N Takasu
- Department of Physiology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
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23
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Abstract
Melatonin is of great importance to the investigation of human biological rhythms. Its rhythm in plasma or saliva provides the best available measure of the timing of the internal circadian clock. Its major metabolite 6-sulphatoxymelatonin is robust and easily measured in urine. It thus enables long-term monitoring of human rhythms in real-life situations where rhythms may be disturbed, and in clinical situations where invasive procedures are difficult. Melatonin is not only a "hand of the clock"; endogenous melatonin acts to reinforce the functioning of the human circadian system, probably in many ways. Most is known about its relationship to sleep and the decline in core body temperature and alertness at night. Current perspectives also include a possible influence on major disease risk, arising from circadian rhythm disruption. Melatonin clearly has the ability to induce sleepiness and lower core body temperature during "biological day" and to change the timing of human rhythms when treatment is appropriately timed. It can entrain free-running rhythms and maintain entrainment in most blind and some sighted people. Used therapeutically it has proved a successful treatment for circadian rhythm disorder, particularly the non-24-h sleep wake disorder of the blind. Numerous other clinical applications are under investigation. There are, however, areas of controversy, large gaps in knowledge, and insufficient standardization of experimental conditions and analysis for general conclusions to be drawn with regard to most situations. The future holds much promise for melatonin as a therapeutic treatment. Most interesting, however, will be the dissection of its effects on human genes.
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Affiliation(s)
- Josephine Arendt
- Centre for Chronobiology, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey, United Kingdom.
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Wehr TA, Aeschbach D, Duncan WC. Evidence for a biological dawn and dusk in the human circadian timing system. J Physiol 2001; 535:937-51. [PMID: 11559786 PMCID: PMC2278827 DOI: 10.1111/j.1469-7793.2001.t01-1-00937.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2000] [Accepted: 05/16/2001] [Indexed: 11/27/2022] Open
Abstract
1. Because individuals differ in the phase angle at which their circadian rhythms are entrained to external time cues, averaging group data relative to clock time sometimes obscures abrupt changes that are characteristic of waveforms of the rhythms in individuals. Such changes may have important implications for the temporal organization of human circadian physiology. 2. To control for variance in phase angle of entrainment, we used dual internal reference points--onset and offset of the nocturnal period of melatonin secretion--to calculate average profiles of circadian rhythm data from five previously published studies. 3. Onset and/or offset of melatonin secretion were found to coincide with switch-like transitions between distinct diurnal and nocturnal periods of circadian rhythms in core body temperature, sleepiness, power in the theta band of the wake EEG, sleep propensity and rapid eye movement (REM) sleep propensity. 4. Transitions between diurnal and nocturnal periods of sleep-wake and cortisol circadian rhythms were found to lag the other transitions by 1-3 h. 5. When the duration of the daily light period was manipulated experimentally, melatonin-onset-related transitions in circadian rhythms appeared to be entrained to the light-to-dark transition, while melatonin-offset-related transitions appeared to be entrained to the dark-to-light transition. 6. These results suggest a model of the human circadian timing system in which two states, one diurnal and one nocturnal, alternate with one another, and in which transitions between the states are switch-like and are separately entrained to dawn and dusk. 7. This description of the human circadian system is similar to the Pittendrigh-Daan model of the rodent circadian system, and it suggests that core features of the system in other mammals are conserved in humans.
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Affiliation(s)
- T A Wehr
- Section on Biological Rhythms, NIMH, Building 10, Room 3S-231, 10 Center Drive MSC1390, Bethesda, MD 20892-1390, USA.
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Abstract
Most of the anatomical and molecular substrates of the system that encodes changes in photoperiod in the duration of melatonin secretion, and the receptor molecules that read this signal, have been shown to be conserved in monkeys and humans, and the functions of this system appear to be intact from the level of the retina to the level of the melatonin-duration signal of change of season. While photoperiodic seasonal breeding has been shown to occur in monkeys, it remains unclear whether photoperiod and mediation of photoperiod's effects by melatonin influence human reproduction. Epidemiological evidence suggests that inhibition of fertility by heat in men in summer contributes to seasonal variation in human reproduction at lower latitudes and that stimulation of fertility by lengthening of the photoperiod in spring contributes to the variation at higher latitudes. Parallels between the seasonality of human reproduction and seasonal affective disorder suggest that they may be governed by common biological processes. Historical and experimental evidence indicates that human responses to seasonal changes in the natural photoperiod may have been more robust prior to the Industrial Revolution and that subsequently they have been increasingly suppressed by alterations of the physical environment.
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Affiliation(s)
- T A Wehr
- Section on Biological Rhythms, National Institute of Mental Health, Bethesda, MD, USA
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Daan S, Albrecht U, van der Horst GT, Illnerová H, Roenneberg T, Wehr TA, Schwartz WJ. Assembling a clock for all seasons: are there M and E oscillators in the genes? J Biol Rhythms 2001; 16:105-16. [PMID: 11302553 DOI: 10.1177/074873001129001809] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The hypothesis is advanced that the circadian pacemaker in the mammalian suprachiasmatic nucleus (SCN) is composed at the molecular level of a nonredundant double complex of circadian genes (per1, cry1, and per2, cry2). Each one of these sets would be sufficient for the maintenance of endogenous rhythmicity and thus constitute an oscillator. Each would have slightly different temporal dynamics and light responses. The per1/cry1 oscillator is accelerated by light and decelerated by darkness and thereby tracks dawn when day length changes. The per2 /cry2 oscillator is decelerated by light and accelerated by darkness and thereby tracks dusk. These M (morning) and E (evening) oscillators would give rise to the SCN's neuronal activity in an M and an E component. Suppression of behavioral activity by SCN activity in nocturnal mammals would give rise to adaptive tuning of the endogenous behavioral program to day length. The proposition-which is a specification of Pittendrigh and Daan's E-M oscillator model-yields specific nonintuitive predictions amenable to experimental testing in animals with mutations of circadian genes.
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Affiliation(s)
- S Daan
- Zoological Laboratory, University of Groningen, Haren, The Netherlands
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Lewy AJ. Melatonin as a marker and phase-resetter of circadian rhythms in humans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 460:425-34. [PMID: 10810544 DOI: 10.1007/0-306-46814-x_51] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- A J Lewy
- Department of Psychiatry, Oregon Health Sciences University, Portland 97201, USA
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Arendt J. Is melatonin a photoperiodic signal in humans? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 460:417-24. [PMID: 10810543 DOI: 10.1007/0-306-46814-x_50] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- J Arendt
- School of Biological Sciences, University of Surrey, Guildford, UK
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Putilov AA, Russkikh GS, Danilenko KV. Phase of melatonin rhythm in winter depression. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 460:441-58. [PMID: 10810546 DOI: 10.1007/0-306-46814-x_53] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- A A Putilov
- Institute for Medical and Biological Cybernetics, Siberian Branch, RAMS, Novosibirsk, Russia.
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Wright KP, Badia P. Effects of menstrual cycle phase and oral contraceptives on alertness, cognitive performance, and circadian rhythms during sleep deprivation. Behav Brain Res 1999; 103:185-94. [PMID: 10513586 DOI: 10.1016/s0166-4328(99)00042-x] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The influence of menstrual cycle phase and oral contraceptive use on neurobehavioral function and circadian rhythms were studied in healthy young women (n = 25) using a modified constant routine procedure during 24 h of sleep deprivation. Alertness and performance worsened across sleep deprivation and also varied with circadian phase. Entrained circadian rhythms of melatonin and body temperature were evident in women regardless of menstrual phase or oral contraceptive use. No significant difference in melatonin levels, duration, or phase was observed between women in the luteal and follicular phases, whereas oral contraceptives appeared to increase melatonin levels. Temperature levels were higher in the luteal phase and in oral contraceptive users compared to women in the follicular phase. Alertness on the maintenance of wakefulness test and some tests of cognitive performance were poorest for women in the follicular phase especially near the circadian trough of body temperature. These observations suggest that hormonal changes associated with the menstrual cycle and the use of oral contraceptives contribute to changes in nighttime waking neurobehavioral function and temperature level whereas these factors do not appear to affect circadian phase.
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Affiliation(s)
- K P Wright
- Sleep and Psychophysiology Research Laboratory, Department of Psychology, Bowling Green State University, OH 43403, USA.
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Penev PD, Zee PC, Turek FW. Quantitative analysis of the age-related fragmentation of hamster 24-h activity rhythms. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:R2132-7. [PMID: 9435671 DOI: 10.1152/ajpregu.1997.273.6.r2132] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The continuous monitoring of spontaneous locomotor activity has emerged as one of the most widely used metrics in rodent circadian research. This behavioral measure is also extremely useful for the description of the effects of aging on circadian rhythms. The present study describes the successful use of a log-survivorship approach to identify discrete bouts of hamster wheel-running activity and provides a detailed description of the age-related fragmentation in the 24-h profile of this behavioral variable. In addition, stepwise discriminant analysis identified the most important quantitative measures for distinguishing between the individual patterns of wheel-running activity of young (3 mo) and old (17-18 mo) golden hamsters. The results suggest that this method of bout analysis can be a valuable tool for the study of genetic, developmental, neurochemical, physiological, and environmental factors involved in the temporal control of rodent locomotor behavior.
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Affiliation(s)
- P D Penev
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA
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Abstract
Administration of melatonin is useful in the treatment of desynchronized conditions. The mechanisms through which melatonin exerts its effect are not completely clear. Melatonin exerts direct effects on several biological functions, such as the regulation of body temperature, but there is no proof that these actions are important in the indirect regulation of main pacemaker activity. By contrast, it is very likely that melatonin exerts direct effects on circadian clocks, and that depending on the time of its administration/presence, it antagonizes or promotes the phase-shifting effects exerted by light. It is possible that melatonin regulates its own secretion and that its prolonged or shortened secretion in the period of the night-day transition is responsible for the lengthening or shortening, respectively, of the nocturnal melatonin rise. This possibility that needs to be confirmed by extensive studies may represent a physiological mechanism through which photoperiodic information is more rapidly and efficiently transformed by melatonin in a circadian signal to all the body.
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Affiliation(s)
- A Cagnacci
- Istituto di Fisiopatologia della Riproduzione Umana, Università di Modena, Italy
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Oren DA, Giesen HA, Wehr TA. Restoration of detectable melatonin after entrainment to a 24-hour schedule in a 'free-running' man. Psychoneuroendocrinology 1997; 22:39-52. [PMID: 9141150 DOI: 10.1016/s0306-4530(96)00038-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We evaluated a 37-year-old male with a non-24-h sleep-wake disorder. His environment gave him little exposure to bright light. Circadian profiles of temperature, melatonin, thyrotropin, cortisol and testosterone were obtained along with endocrine challenges of the thyroid, adrenal, growth hormone and gonadal axes. Multiple endocrine abnormalities were detected. Testosterone was low and nocturnal thyrotropin levels were erratic. Serum melatonin was undetectable throughout the day and night on multiple occasions, and responses to infusions of TRH, GnRH and GRF-44 were abnormal. Responses to CRH infusion were normal. The patient was successfully entrained to a 24-h schedule by daily exposure to 2500 lux light from 0700h to 0900h, avoidance of light (by wearing dark goggles) from 1800h to 2300h, and strict enforcement of a dark environment from 2300h to 0700h. After entrainment, a normal pattern of nocturnal melatonin secretion was found. GH response to GRF-44 also normalized, although abnormal responses to TRH and GnRH persisted. This case raises the possibility that a complex interaction of light exposure with the circadian system can reversibly suspend pineal gland secretion of melatonin indefinitely. It also suggests that circadian rhythm disorders be considered in the differential diagnosis of abnormal endocrine function.
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Affiliation(s)
- D A Oren
- DVA, Psychiatry 116A, Yale School of Medicine, West Haven, CT 06516, USA. Oren.Dan_A+@West-Haven.VA.gov
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Abstract
The role exerted by melatonin in human physiology has not been completely ascertained. Melatonin levels have been measured in different physiopathological conditions, but the effects induced by melatonin administration or withdrawal have been tested only recently. Some effects have been clearly documented. Melatonin has hypothermic properties, and its nocturnal secretion generates about 40% of the amplitude of the circadian body temperature rhythm. Melatonin has sleep inducing properties, and exerts important activities in the regulation of circadian rhythms. Melatonin is capable of phase shifting human circadian rhythms, of entraining free-running circadian rhythms, and of antagonizing phase shifts induced by nighttime exposure to light. Its effect on human reproduction is not completely clear, but stimulatory effects on gonadotropin secretion have been reported in the follicular phase of the menstrual cycle. Direct actions on ovarian cells and spermatozoa have been also documented. Beside these, new important actions for melatonin may be proved. Melatonin may exert protective effects on the cardiovascular system, by reducing the risk of atherosclerosis and hypertension, and may influence immune responses. Finally, by acting as an antioxidant, melatonin could be important in slowing the processes of ageing.
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Affiliation(s)
- A Cagnacci
- Institute of Obstetrics and Gynecology, University of Modena, Italy
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Abstract
The chronic effects of antidepressant drugs (ADs) on circadian rhythms of behavior, physiology and endocrinology are reviewed. The timekeeping properties of several classes of ADs, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, serotonin agonists and antagonists, benzodiazepines, and melatonin are reviewed. Pharmacological effects on the circadian amplitude and phase, as well as effects on day-night measurements of motor activity, sleep-wake, body temperature (Tb), 3-methoxy-4-hydroxyphenylglycol, cortisol, thyroid hormone, prolactin, growth hormone and melatonin are examined. ADs often lower nocturnal Tb and affect the homeostatic regulation of sleep. ADs often advance the timing and decrease the amount of slow wave sleep, reduce rapid eye movement sleep and increase or decrease arousal. Together, AD effects on nocturnal Tb and sleep may be related to their therapeutic properties. ADs sometimes delay nocturnal cortisol timing and increase nocturnal melatonin, thyroid hormone and prolactin levels; these effects often vary with diagnosis, and clinical state. The effects of ADs on the coupling of the central circadian pacemaker to photic and nonphotic zeitgebers are discussed.
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Affiliation(s)
- W C Duncan
- Clinical Psychobiology Branch, National Institute of Mental Health, NIH, Bethesda, MD 20892, USA
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