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Cajochen C, Reichert CF, Münch M, Gabel V, Stefani O, Chellappa SL, Schmidt C. Ultradian sleep cycles: Frequency, duration, and associations with individual and environmental factors-A retrospective study. Sleep Health 2024; 10:S52-S62. [PMID: 37914631 DOI: 10.1016/j.sleh.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 09/04/2023] [Accepted: 09/06/2023] [Indexed: 11/03/2023]
Abstract
OBJECTIVE Sleep varies between individuals in response to sleep-wake history and various environmental factors, including light and noise. Here we report on the intranight variation of the ultradian nonrapid eye movement-rapid eye movement (NREM-REM) sleep cycle in 369 participants who have contributed to different laboratory studies from 1994 to 2020 at the Centre for Chronobiology, Basel, Switzerland. RESULTS We observed a large interindividual variability in sleep cycle duration, including NREM and REM sleep episodes in healthy participants who were given an 8-hour sleep opportunity at habitual bedtime in controlled laboratory settings. The median sleep cycle duration was 96 minutes out of 6064 polysomnographically-recorded cycles. The number and duration of cycles were not normally distributed, and the distribution became narrower for NREM sleep and wider for REM sleep later in the night. The first cycle was consistently shorter than subsequent cycles, and moderate presleep light or nocturnal noise exposure had no significant effects on ultradian sleep cycle duration. Age and sex significantly affected NREM and REM sleep duration, with older individuals having longer NREM and shorter REM sleep particularly in the end of the night, and females having longer NREM sleep episodes. High sleep pressure (ie, sleep deprivation) and low sleep pressure (ie, multiple naps) altered ultradian sleep cycles, with high sleep pressure leading to longer NREM sleep in the first cycle, and low sleep pressure leading to longer REM sleep episodes. Positive correlations were observed between N2 and NREM duration, and between N1 and REM duration. Weak intrasleep REM sleep homeostasis was also evident in our data set. CONCLUSIONS We conclude that ultradian sleep cycles are endogenous biological rhythms modulated by age, sex, and sleep homeostasis, but not directly responsive to (moderate levels of) environmental cues in healthy good sleepers.
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Affiliation(s)
- Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland.
| | - Carolin Franziska Reichert
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Mirjam Münch
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | | | - Oliver Stefani
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland; Research Cluster Molecular and Cognitive Neurosciences (MCN), University of Basel, Basel, Switzerland
| | - Sarah Laxhmi Chellappa
- School of Psychology, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Christina Schmidt
- Sleep & Chronobiology Group, GIGA-CRC-In Vivo Imaging Research Unit, University of Liège, Liège, Belgium; Psychology and Neuroscience of Cognition Research Unit (PsyNCog), Faculty of Psychology, Speech and Language, University of Liège, Liège, Belgium
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Baselgia S, Combertaldi SL, Fahr A, Wirz DS, Ort A, Rasch B. Pre-sleep arousal induced by suspenseful series and cliffhangers have only minor effects on sleep: A sleep laboratory study. Sleep Med 2023; 102:186-198. [PMID: 36701833 DOI: 10.1016/j.sleep.2023.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 12/22/2022] [Accepted: 01/06/2023] [Indexed: 01/13/2023]
Abstract
Pre-sleep arousal impairs sleep. Therefore, watching suspenseful TV series before sleep is not recommended as they increase arousal. In particular, the consumption of multiple episodes of the same suspenseful TV series in one sitting - termed binge-watching - could lead to large increases in physiological arousal delaying sleep onset. Furthermore, abrupt endings during critical scenes - termed cliffhangers - result in unfinished story lines, which further increase cognitive arousal and could negatively impact sleep architecture and the number of awakenings. However, the effects of binge-watching and cliffhangers on objective sleep parameters are still unknown. Here we tested in a controlled sleep-laboratory setting whether pre-sleep arousal induced by watching 3-4 episodes of a suspenseful TV series has negative effects on sleep in 50 healthy young participants (39 females, mean age = 22.62 ± 2.60 (SD)). Watching a neutral TV series served as a control condition, according to a within-subject design. In one group of participants, the suspenseful TV series ended with a cliffhanger. In the other group, the same TV series ended where no ongoing action was interrupted. Pre-sleep arousal was measured both subjectively with the self-reported level of stress and objectively with the mean heart rate and cortisol level. As expected, suspenseful TV series induced higher cognitive and physiological pre-sleep arousal than neutral control TV series, with highest values for TV series with cliffhangers. In spite of the high pre-sleep arousal, participants fell asleep faster after watching the suspenseful compared with the neutral TV series (F(1,48) = 4.89, p = 0.032, η2 = 0.09). Sleep architecture and the number of awakenings remained unaffected. However, in the first two sleep cycles, heart rate was still higher after watching suspenseful TV series (F(1,48) = 6.76, p = 0.012, η2 = 0.12). And only after cliffhangers, objective sleep quality - measured as the ratio between slow-wave and beta activity during sleep - was lower than in the other conditions (interaction effect, F(1,48) = 5.05, p = 0.029, η2 = 0.10). Our results speak against large impairments of pre-sleep watching of multiple episodes of suspenseful TV series and cliffhangers on sleep quality and architecture. However, unfinished narratives might induce more subtle changes in oscillatory power during sleep, possibly reflecting ongoing cognitive processing during sleep.
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Affiliation(s)
- Sandrine Baselgia
- Department of Psychology, University of Fribourg, Fribourg, Switzerland
| | | | - Andreas Fahr
- Department of Communication and Media Research, University of Fribourg, Fribourg, Switzerland
| | - Dominique Stefanie Wirz
- Department of Communication and Media Research, University of Fribourg, Fribourg, Switzerland
| | - Alexander Ort
- Department of Health Sciences and Medicine, University of Lucerne, Lucerne, Switzerland
| | - Björn Rasch
- Department of Psychology, University of Fribourg, Fribourg, Switzerland.
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Combertaldi SL, Ort A, Cordi M, Fahr A, Rasch B. Pre-sleep social media use does not strongly disturb sleep: a sleep laboratory study in healthy young participants. Sleep Med 2021; 87:191-202. [PMID: 34627122 DOI: 10.1016/j.sleep.2021.09.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/17/2021] [Accepted: 09/10/2021] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Sleep is critical for our mental health and optimal cognitive functioning. Social media use is increasingly common and suspected to disturb sleep due to increasing bedtime arousal. However, most studies rely on self-reported sleep. METHODS We tested the effects of 30 min social media use on arousal and subsequent sleep in the sleep laboratory in 32 healthy young volunteers. Effects of blue-light were excluded in this study. We compared it to 30 min progressive muscle relaxation (PMR) and neutral sleep in a within-subject design. RESULTS Thirty minutes of social media use immediately before sleep did not significantly increase arousal and did neither disturb objective nor subjective sleep. After social media use, participants only spent less time in sleep stage N2. In contrast, PMR had the expected positive effects on pre-sleep arousal level indicated by reduced heart rate. In addition, PMR improved sleep efficiency, reduced sleep onset latency, and shortened the time to reach slow-wave sleep compared to a neutral night. Oscillatory power in the slow-wave activity and spindle bands remained unaffected. CONCLUSION Social media use before sleep (controlling for effects of blue-light) had little effect on bedtime arousal and sleep quality than what was previously expected. The most notable effect appears to be the additional time spent engaging in social media use at bedtime, potentially keeping people from going to sleep. As wake up-time is mostly determined externally, due to school or working hours, limiting personal media use at bedtime-and especially in bed-is recommended to get sufficient hours of sleep.
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Affiliation(s)
| | - Alexander Ort
- University of Lucerne, Department of Health Sciences and Medicine, Lucerne, Switzerland
| | - Maren Cordi
- University of Fribourg, Department of Psychology, Fribourg, Switzerland
| | - Andreas Fahr
- University of Fribourg, Department of Communication and Media Research, Fribourg, Switzerland
| | - Björn Rasch
- University of Fribourg, Department of Psychology, Fribourg, Switzerland.
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Blume C, Cajochen C. 'SleepCycles' package for R - A free software tool for the detection of sleep cycles from sleep staging. MethodsX 2021; 8:101318. [PMID: 34434837 PMCID: PMC8374325 DOI: 10.1016/j.mex.2021.101318] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/19/2021] [Indexed: 11/24/2022] Open
Abstract
The detection of NREM-REM sleep cycles in human sleep data (i.e., polysomnographically assessed sleep stages) enables fine-grained analyses of ultradian variations in sleep microstructure (e.g., sleep spindles, and arousals), or other amplitude- and frequency-specific electroencephalographic features during sleep. While many laboratories have software that is used internally, reproducibility requires the availability of open-source software. Therefore, we here introduce the ‘SleepCycles’ package for R, an open-source software package that identifies sleep cycles and their respective (non-) rapid eye movement ([N]REM) periods from sleep staging data. Additionally, each (N)REM period is subdivided into parts of equal duration (percentiles), which may be useful for further fine-grained analyses. The detection criteria used in the package are, with some adaptations, largely based on criteria originally proposed by Feinberg and Floyd (1979). The latest version of the package can be downloaded from the Comprehensive R Archives Network (CRAN).The package ‘SleepCycles’ for R allows to identify sleep cycles and their respective NREM and REM periods from sleep staging results. Besides the cycle detection, NREM and REM periods are also split into parts of equal duration (percentiles) thereby allowing for a better temporal resolution across the night and comparisons of sleep cycles with different durations amongst different night recordings.
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Affiliation(s)
- Christine Blume
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Basel, Switzerland
| | - Christian Cajochen
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
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Schmidt FP, Herzog J, Schnorbus B, Ostad MA, Lasetzki L, Hahad O, Schäfers G, Gori T, Sørensen M, Daiber A, Münzel T. The impact of aircraft noise on vascular and cardiac function in relation to noise event number: a randomized trial. Cardiovasc Res 2020; 117:1382-1390. [PMID: 32914847 PMCID: PMC8064430 DOI: 10.1093/cvr/cvaa204] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/01/2020] [Accepted: 07/02/2020] [Indexed: 12/13/2022] Open
Abstract
Aims Nighttime aircraft noise exposure has been associated with increased risk of hypertension and myocardial infarction, mechanistically linked to sleep disturbance, stress, and endothelial dysfunction. It is unclear, whether the most widely used metric to determine noise exposure, equivalent continuous sound level (Leq), is an adequate indicator of the cardiovascular impact induced by different noise patterns. Methods and results In a randomized crossover study, we exposed 70 individuals with established cardiovascular disease or increased cardiovascular risk to two aircraft noise scenarios and one control scenario. Polygraphic recordings, echocardiography, and flow-mediated dilation (FMD) were determined for three study nights. The noise patterns consisted of 60 (Noise60) and 120 (Noise120) noise events, respectively, but with comparable Leq, corresponding to a mean value of 45 dB. Mean value of noise during control nights was 37 dB. During the control night, FMD was 10.02 ± 3.75%, compared to 7.27 ± 3.21% for Noise60 nights and 7.21 ± 3.58% for Noise120 nights (P < 0.001). Sleep quality was impaired after noise exposure in both noise scenario nights (P < 0.001). Serial echocardiographic assessment demonstrated an increase in the E/E′ ratio, a measure of diastolic function, within the three exposure nights, with a ratio of 6.83 ± 2.26 for the control night, 7.21 ± 2.33 for Noise60 and 7.83 ± 3.07 for Noise120 (P = 0.043). Conclusions Nighttime exposure to aircraft noise with similar Leq, but different number of noise events, results in a comparable worsening of vascular function. Adverse effects of nighttime aircraft noise exposure on cardiac function (diastolic dysfunction) seemed stronger the higher number of noise events.
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Affiliation(s)
- Frank P Schmidt
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Johannes Herzog
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Boris Schnorbus
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Mir Abolfazl Ostad
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Larissa Lasetzki
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Omar Hahad
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Mainz, Germany
| | - Gianna Schäfers
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| | - Tommaso Gori
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Mainz, Germany
| | - Mette Sørensen
- Diet, Genes and Environment Unit, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Andreas Daiber
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Mainz, Germany
| | - Thomas Münzel
- Department of Cardiology I, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Mainz, Germany
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