Adverse events associated with oral administration of melatonin: A critical systematic review of clinical evidence

Melatonin's paradox: From therapeutic benefits to toxicity warnings

Melatonin is an endogenous chemical predominantly synthesized in the pineal gland, widely recognized for its hormonal roles, such as regulating sleep and circadian rhythms. Through mechanisms such as anti-oxidative reduction, anti-inflammatory, and immunomodulation, it is suggested that melatonin exhibits biochemical properties in in vitro conditions. Beyond these functions, melatonin has garnered attention for its pharmacological benefits, particularly as a therapeutic agent that is exogenously administered as a supplement in various diseases ranging from insomnia to immunological and gastrointestinal disorders. However, emerging studies highlight potential toxicological concerns associated with exogenous melatonin use, especially in specific populations. This review provided a comprehensive exploration of melatonin's dual role as a therapeutic and potentially toxic agent. It summarized what is currently known about its pharmacological, toxicological, and biochemical characteristics as well as toxicity mechanisms, and safety concerns in susceptible groups. By highlighting new knowledge gaps about melatonin's clinical uses, the study opens the door for further studies to maximize its therapeutic benefits while maintaining its safety.

Association between sleep disturbance and metabolic dysfunctions in adipose tissue: Insights into melatonin's role

The increased prevalence of sleep disturbances in modern society is frequently linked to various metabolic disorders, including insulin resistance, obesity, hypertension, fatty liver disease, and cardiometabolic complications. Melatonin, a pineal gland-secreted neurohormone, plays a pivotal role in maintaining the circadian rhythm. It is involved in regulating adipose tissue development, lipid accumulation, browning of white adipose tissue, and activation of brown adipose tissue. The adipose tissue is a dynamic endocrine organ that secretes hormones and cytokines. Recent research has highlighted the significant role of melatonin in the modulation of lipid metabolism, adipogenesis, and thermogenesis in adipose tissues. Circadian rhythms are important in synchronizing metabolic functions with environmental cues, such as light and dark, feeding-fasting states, etc. Irregular sleep patterns, shift work, and exposure to artificial light at night disrupt these rhythms, affecting circadian regulation and compromising metabolic health. Melatonin imbalance due to sleep disturbances results in metabolic dysfunction, increased fat storage, and adipose tissue inflammation. As circadian rhythm and melatonin are both related, a change in circadian rhythm affects the physiology of adipose tissues thereby precipitating metabolic complications through melatonin signaling. This study attempted to understand the mechanisms by which melatonin influences adipose tissue activity, highlighting the role of circadian rhythms in this process. This will enable the development of melatonin-based therapies to mitigate the adverse effects of chronobiological disturbances on the physiology of adipose tissue. Understanding these interactions will provide novel insights for combating obesity and related metabolic conditions.

Melatonin MT1 Receptor Expression in Luminal Invasive Ductal Breast Carcinoma in Postmenopausal Women

Laboratory and animal studies indicate that melatonin exerts a negative impact on breast cancer progression and metastasis. These actions are both receptor-dependent and -independent. Of the two transmembrane melatonin receptors identified in humans, breast cancer expresses only MT1. The aim of this study was to investigate the expression of MT1 in hormone-receptor-positive, HER2-negative invasive ductal breast carcinoma in postmenopausal women and its possible correlations with clinicopathological parameters and survival. A total of 118 patients with luminal A/B primary breast cancer with or without axillary metastases were identified. The MT1 receptor expression was immunohistochemically assessed as a percentage of stained cells and a weighted index (WI) (percentage multiplied by staining intensity). Most tumor samples (84.7%) and metastasized lymph nodes (96%) stained positive for MT1, with varying intensity. No statistically significant correlations were found between the MT1 expression or the WI in the primary tumor and the patient and tumor characteristics, or the MT1 and WI in the metastasized lymph nodes. The survival analysis did not reveal a significant effect of MT1 expression or the WI on the risk of recurrence or survival.

The Role of Diet and Oral Supplementation for the Management of Diabetic Retinopathy and Diabetic Macular Edema: A Narrative Review

Globally, diabetic retinopathy (DR) and diabetic macular edema (DME) are the leading causes of visual loss in working people. Current treatment approaches mostly target proliferative DR and DME, such as intravitreal injections of antivascular endothelial growth factor agents and laser photocoagulation. Before DR progresses into the more severe, sight-threatening proliferative stage, patients with early stages of the disease must get early and appropriate care. It has been suggested that nutraceuticals, which are natural functional foods with minimal adverse effects, may help diabetic patients with DR and DME. Several in vitro and in vivo studies were carried out over the last years, showing the potential benefits of several nutraceuticals in DR due to their neuroprotective, vasoprotective, anti-inflammatory, and antioxidant properties. Although most of the research is restricted to animal models and many nutraceuticals have low bioavailability, these compounds may adjuvate and implement conventional DR therapies. The purpose of this review is (i) to summarize the complex pathophysiology underlying DR and DME and (ii) to examine the main natural-derived molecules and dietary habits that can assist conventional therapies for the clinical management of DR and DME.

Optimizing Sleep Disorder Management in Hospitalized Patients: Practical Approach for Healthcare Providers

PURPOSE

To provide a comprehensive review of sleep disturbances in hospitalized patients, focusing on a case-based approach to illustrate the multifaceted nature of this clinical challenge.

METHOD

An extensive review of related literature was conducted to determine the common causes of sleep disturbances in hospitalized patients, such as environmental, medical, psychological, and physiological factors. The case of Mrs. Z was used to illustrate how these factors interact in a clinical setting.

FINDINGS

The study revealed a high prevalence of sleep disturbances in hospitalized patients, which can lead to significant adverse outcomes. A multidisciplinary approach involving physicians, nurses, pharmacists, and other healthcare professionals is essential to effectively manage sleep disorders due to the interplay of various factors. Nonpharmacological interventions are fundamental to a comprehensive sleep management plan. Pharmacotherapy may sometimes be necessary to improve sleep quality and duration.

CONCLUSION

Health professionals can significantly enhance the sleep quality of hospitalized piatients by understanding the value of sleep and providing evidence-based strategies for improvement. In return, this improves patient outcomes, reduces healthcare costs, and advances general patient satisfaction.

Efficacy of melatonin vs. midazolam for oral premedication in children: a systematic review and meta-analysis

INTRODUCTION

Achieving appropriate levels of premedication and parental separation is needed for smooth induction of anesthesia and prevention of perioperative complications. Both melatonin and midazolam are used for the premedication in children, but we do not have consensus on which premedication is superior among them.

EVIDENCE ACQUISITION

A systematic review of randomized controlled trials comparing the efficacy and safety of use of midazolam and melatonin as premedication in children aged 1-15 years was conducted. Patients who received drugs other than melatonin or midazolam as premedication were excluded. PubMed, Embase, Scopus, Google Scholar were searched and the last search was done in December 2022.

EVIDENCE SYNTHESIS

Full text of ten articles with a total of 774 participants (442 melatonin, 332 midazolam) were eligible. The data extracted were synthesized after quality assessment. The outcomes appraised included: sedation, anxiety in preoperative room and during induction. Among four studies examining sedation, there were no significant differences between melatonin and midazolam (SMD=0.03, 95% CI - 0.35 to 0.40, P=0.88, I2=81%). There were no significant differences between melatonin and midazolam among two studies examining anxiety in pre-operative room (SMD=-0.04, 95% CI -4.58,4.50, P=0.99, I2=0%) and anxiety during anesthesia induction as an outcome (SMD=-1.38, 95% CI -4.81 to 2.05, P=0.43, I2=0%).

CONCLUSIONS

The review showed that melatonin is comparable to midazolam in achieving sedation for facilitating inhalational induction in pediatric patients. The review showed no significant difference in reduction of anxiety in the preoperative room and during induction of anesthesia when either melatonin or midazolam is used as premedicants. Heterogeneity in premedication doses, parameters assessed, outcomes measured, and scales that quantify efficacy resulted in the inconsistencies in how the medications were compared and hence resulted in difficulties in data synthesis. Future studies comparing efficacy of premedication need to consider the proposed standardizations in methodology for achieving optimal results that are a fair comparison of the two medications.

Melatonin's Impact on Wound Healing

Melatonin (5-methoxy-N-acetyltryptamine) is an indoleamine compound that plays a critical role in the regulation of circadian rhythms. While melatonin is primarily synthesized from the amino acid tryptophan in the pineal gland of the brain, it can also be produced locally in various tissues, such as the skin and intestines. Melatonin's effects in target tissues can be mediated through receptor-dependent mechanisms. Additionally, melatonin exerts various actions via receptor-independent pathways. In biological systems, melatonin and its endogenous metabolites often produce similar effects. While injuries are common in daily life, promoting optimal wound healing is essential for patient well-being and healthcare outcomes. Beyond regulating circadian rhythms as a neuroendocrine hormone, melatonin may enhance wound healing through (1) potent antioxidant properties, (2) anti-inflammatory actions, (3) infection control, (4) regulation of vascular reactivity and angiogenesis, (5) analgesic (pain-relieving) effects, and (6) anti-pruritic (anti-itch) effects. This review aims to provide a comprehensive overview of scientific studies that demonstrate melatonin's potential roles in supporting effective wound healing.

Effects of melatonin supplementation on markers of inflammation and oxidative stress in patients with diabetes: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Diabetes mellitus is a metabolic disorder, in which chronic systemic inflammation and oxidative stress contribute to the progression of this condition and its complications. Melatonin, a hormone known for its potent antioxidant and anti-inflammatory properties, has emerged as a potential therapeutic intervention in diabetes. This review aims to evaluate the effects of melatonin supplementation on markers of oxidative stress and inflammation in diabetic patients.

METHODS

A thorough literature search of databases, including PubMed, Embase, Web of Science, Cochrane Central, CNKI, and Scopus, was conducted through October 2023. We included randomized controlled trials investigating the effects of melatonin on markers of inflammation and oxidative stress, compared to placebo in patients with diabetes. The data was analyzed using the random-effects model and the summary effect size was determined using the standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

Fourteen studies with 823 participants were included. Our analysis indicates that melatonin can lead to significant reductions in levels of C-reactive protein (CRP) [SMD = -0.75; 95% CI: -1.37, -0.12; P = 0.018], tumor necrosis factor-alpha (TNF-α) [SMD = -0.40; 95% CI: -0.64, -0.15; P = 0.001], interleukin (IL)-1 [SMD = -0.75; 95% CI: -1.03, -0.47; P < 0.0001], IL-6 [SMD = -0.79; 95% CI: -1.07, -0.51; P < 0.0001], and malondialdehyde (MDA) [SMD = -0.61; 95% CI: -0.80, -0.43; P < 0.0001]. Furthermore, we found a significant increase in levels of total antioxidant capacity (TAC) [SMD = 0.81; 95% CI: 0.12, 1.51; P = 0.021], glutathione (GSH) [SMD = 0.66; 95% CI: 0.28, 1.03; P = 0.001], and superoxide dismutase (SOD) [SMD = 1.69; 95% CI: 0.80, 2.58; P < 0.0001] following melatonin consumption in patients with diabetes.

CONCLUSION

Melatonin supplementation is a promising complementary strategy to attenuate oxidative stress and inflammation in diabetic patients.

Comparative Pharmacokinetics of Sustained-Release versus Immediate-Release Melatonin Capsules in Fasting Healthy Adults: A Randomized, Open-Label, Cross-Over Study

Background: Exogenous melatonin, a nutraceutical for maintaining a healthy sleep-wake cycle and managing sleep disorders, requires large, repeated doses due to its low bioavailability and short half-life. This necessitates the development of a sustained-release formulation with a longer half-life and sustained plasma concentration. Therefore, exogenous novel 5 mg sustained-release melatonin capsules (Melatonin-SR, test product) were formulated. Methods: This open-label cross-over study compared the pharmacokinetics (maximum concentration [Cmax], time to reach Cmax [Tmax], area under the curve [AUC], and elimination half-life [t1/2]) and the safety of Melatonin-SR with 5 mg immediate-release melatonin capsules (Melatonin-IR, reference product) after single-dose oral administration in healthy fasting adults. Results: Sixteen participants (aged 18-45 years) were randomized (1:1) to receive either Melatonin-SR or Melatonin-IR in two periods with a 7-day washout period. Melatonin-SR reported a lower Cmax (11,446.87 pg/mL) compared to Melatonin-IR (22,786.30 pg/mL). The mean Tmax of Melatonin-SR and Melatonin-IR was 1.26 h and 0.87 h, respectively. The mean t1/2 of Melatonin-SR (5.10 h) was prolonged by five-fold compared to Melatonin-IR (1.01 h). One adverse event (vomiting) was reported following the administration of the Melatonin-IR. Conclusions: Melatonin-SR resulted in higher and sustained plasma melatonin concentrations for an extended period and was well-tolerated. Hence, Melatonin-SR may be a promising nutraceutical for maintaining healthy sleep.

Melatonin-induced symptomatic bradycardia in an otherwise healthy male: a case report

Melatonin, a pineal gland hormone closely associated with the circadian rhythm, has been trending over the past years as an over-the-counter medication to aid with sleep disturbances. Although generally believed to be safe, recent studies show negative inotropic and chronotropic effects on the heart rate and blood pressure in humans. Several studies suggested that melatonin induces cardiac vagal tone and affects heart rate and mean arterial pressure. Limited literature is currently available on the effects of melatonin beyond its sleep function. We present a case of a healthy 22-year-old male who visited the emergency department reporting palpitations and dizziness following the ingestion of 20 mg of melatonin. Subsequent examinations revealed marked bradycardia. Fortunately, the patient experienced spontaneous resolution of the bradycardia without necessitating intervention after a few hours of observation, and he was observed and discharged.

Significance of Melatonin in the Regulation of Circadian Rhythms and Disease Management

Melatonin, the 'hormone of darkness' is a neuronal hormone secreted by the pineal gland and other extra pineal sites. Responsible for the circadian rhythm and seasonal behaviour of vertebrates and mammals, melatonin is responsible for regulating various physiological conditions and the maintenance of sleep, body weight and the neuronal activities of the ocular sites. With its unique amphiphilic structure, melatonin can cross the cellular barriers and elucidate its activities in the subcellular components, including mitochondria. Melatonin is a potential scavenger of oxygen and nitrogen-reactive species and can directly obliterate the ROS and RNS by a receptor-independent mechanism. It can also regulate the pro- and anti-inflammatory cytokines in various pathological conditions and exhibit therapeutic activities against neurodegenerative, psychiatric disorders and cancer. Melatonin is also found to show its effects on major organs, particularly the brain, liver and heart, and also imparts a role in the modulation of the immune system. Thus, melatonin is a multifaceted candidate with immense therapeutic potential and is still considered an effective supplement on various therapies. This is primarily due to rectification of aberrant circadian rhythm by improvement of sleep quality associated with risk development of neurodegenerative, cognitive, cardiovascular and other metabolic disorders, thereby enhancing the quality of life.

Insomnia in children affected by autism spectrum disorder: The role of melatonin in treatment

The present article explores the connection between insomnia and Autism Spectrum Disorder (ASD), focusing on the efficacy and safety of melatonin treatments as supported by existing research and current guidelines. In this narrative review a group of Italian experts provide an analysis of the various aspects of managing insomnia in children with ASD, highlighting key points that could enhance the quality of life for both patients and their caregivers. This includes the significance of comprehensively understanding the root causes of a child's sleep difficulties for more effective, long-term management. Insomnia, a condition frequently documented in neurodevelopmental disorders such as ASD, greatly affects the lives of patients and caregivers. Recent data show that melatonin-based formulations are effective and safe for treating ASD-related insomnia both short and long term. In particular, prolonged-release melatonin is poised to be the optimal choice for this patient population. This formulation is approved for the treatment of insomnia in children and adolescents aged 2-18 years suffering from ASD and/or Smith-Magenis syndrome, where sleep hygiene measures and behavioral treatments have not been sufficient. In support, emerging research in pediatric settings indicates long-term efficacy and safety, although further research efforts are still needed. Current guidelines recommend managing insomnia and sleep disturbances in ASD using a combination of behavioral and pharmacological methods, primarily melatonin. Recent concerns about accidental melatonin ingestion highlight the need for high purity standards, such as pharmaceutical-grade prolonged-release formulations. The article also summarizes emerging molecular mechanisms from preclinical research, suggesting future therapeutic approaches.

Unintended consequences: college students' melatonin usage, sleep disturbance, and depressive symptoms

With such high rates of undergraduate sleep problems, students have chosen to take melatonin, an over-the-counter supplement that can facilitate sleep. Questions remain as to the effectiveness of melatonin for sleep problems, and questions have emerged about its impact on mental health. Accordingly, the current study examined how ongoing melatonin usage might impact relative changes in college students' sleep disturbance and ultimately their depressive symptoms. The two-wave (baseline and 2-month follow-up), online sample consisted of 331 undergraduates (86% female; Mage = 21.3, SD = 2.4), who reported on melatonin usage, sleep disturbance, and depressive symptoms. Controlling for sleep hygiene, socio-economic status, and gender, our model demonstrated a significant indirect effect from ongoing melatonin usage to depressive symptoms. Specifically, melatonin consumption predicted relative increases in sleep disturbance, which, in turn, predicted corresponding increases in students' depressive symptoms. Given the increasing prevalence of melatonin usage, the potential for unforeseen consequences remains high. Results suggest that the negative consequences of melatonin use can include both college students' mental health and their sleep. Given the efficacy of addressing sleep problems with cognitive or behavioral strategies, it is essential that student support services highlight alternatives to melatonin and the potential problems associated with its use.

Melatonin and Vascular Function

The indolamine hormone melatonin, also known as N-acetyl-5-methoxytrypamine, is frequently associated with circadian rhythm regulation. Light can suppress melatonin secretion, and photoperiod regulates melatonin levels by promoting its production and secretion at night in response to darkness. This hormone is becoming more and more understood for its functions as an immune-modulatory, anti-inflammatory, and antioxidant hormone. Melatonin may have a major effect on several diabetes-related disturbances, such as hormonal imbalances, oxidative stress, sleep disturbances, and mood disorders, according to recent research. This has raised interest in investigating the possible therapeutic advantages of melatonin in the treatment of diabetic complications. In addition, several studies have described that melatonin has been linked to the development of diabetes, cancer, Alzheimer's disease, immune system disorders, and heart diseases. In this review, we will highlight some of the functions of melatonin regarding vascular biology.

Effects of melatonin on blood pressure, arterial stiffness and quality of life in postmenopausal women: A randomized controlled trial

OBJECTIVES

Studies suggest that melatonin may promote cardiovascular protection. Previous trials have primarily been performed on co-morbid patients. Little information exist on the effect in postmenopausal women with general good health.

DESIGN, PARTICIPANTS AND INTERVENTION

In a double-blinded placebo-controlled study, we randomized 41 postmenopausal women to either 10 mg melatonin per day or placebo for 3 months.

OUTCOME MEASURES

Outcomes of the trial was changes in blood pressure, pulse wave velocity (PWV), and quality of sleep evaluated by Pittsburgh Sleep Quality Index (PSQI).

RESULTS

Thirty-nine women completed the study. Mean age was 63 years (range 55-75 years). Over the 3 months of the trial, PWV did not differ between groups: Placebo 1.1% (IQR -2.1;9.9) vs. melatonin 0.0% (IQR-9.8;4.1), p = 0.43). The were no significant differences in blood pressure bewteen melatonin and placebo group. Both groups had a pour quality of sleep at baseline (placebo: PSQI 6.0 (IQR 3.3; 8.8) vs. melatonin PSQI 6.0 (IQR 3.0; 10.0), p = 0.94), which did not change in response to treatment.

CONCLUSION

In healthy postmenopausal women, supplementation with 10 mg melatonin was well-tolerated, but we did not observe any significant improvements in pulse wave velocity, blood pressure or quality of sleep compared with placebo.

The Potential of Integrative Cancer Treatment Using Melatonin and the Challenge of Heterogeneity in Population-Based Studies: A Case Report of Colon Cancer and a Literature Review

Melatonin is a multifunctional hormone regulator that maintains homeostasis through circadian rhythms, and desynchronization of these rhythms can lead to gastrointestinal disorders and increase the risk of cancer. Preliminary clinical studies have shown that exogenous melatonin alleviates the harmful effects of anticancer therapy and improves quality of life, but the results are still inconclusive due to the heterogeneity of the studies. A personalized approach to testing clinical parameters and response to integrative treatment with nontoxic and bioavailable melatonin in patient-centered N-of-1 studies deserves greater attention. This clinical case of colon cancer analyzes and discusses the tumor pathology, the adverse effects of chemotherapy, and the dynamics of markers of inflammation (NLR, LMR, and PLR ratios), tumors (CEA, CA 19-9, and PSA), and hemostasis (D-dimer and activated partial thromboplastin time). The patient took melatonin during and after chemotherapy, nutrients (zinc, selenium, vitamin D, green tea, and taxifolin), and aspirin after chemotherapy. The patient's PSA levels decreased during CT combined with melatonin (19 mg/day), and melatonin normalized inflammatory markers and alleviated symptoms of polyneuropathy but did not help with thrombocytopenia. The results are analyzed and discussed in the context of the literature on oncostatic and systemic effects, alleviating therapy-mediated adverse effects, association with survival, and N-of-1 studies.

The latest emerging drugs for the treatment of diabetic cardiomyopathy

INTRODUCTION

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus involving multiple pathophysiologic mechanisms. In addition to hypoglycemic agents commonly used in diabetes, metabolism-related drugs, natural plant extracts, melatonin, exosomes, and rennin-angiotensin-aldosterone system are cardioprotective in DCM. However, there is a lack of systematic summarization of drugs for DCM.

AREAS COVERED

In this review, the authors systematically summarize the most recent drugs used for the treatment of DCM and discusses them from the perspective of DCM pathophysiological mechanisms.

EXPERT OPINION

We discuss DCM drugs from the perspective of the pathophysiological mechanisms of DCM, mainly including inflammation and metabolism. As a disease with multiple pathophysiological mechanisms, the combination of drugs may be more advantageous, and we have discussed some of the current studies on the combination of drugs.

Investigating the safety profiles of exogenous melatonin and associated adverse events: A pharmacovigilance study using WHO-VigiBase

Melatonin, a pineal hormone that modulates circadian rhythms, sleep, and neurotransmitters, is widely used to treat sleep disorders. However, there are limited studies on the safety of melatonin. Therefore, we aimed to present the overall patterns of adverse events (AEs) following melatonin administration and identify potential safety signals associated with melatonin. Using VigiBase, a global individual case safety report (ICSRs) database managed by the World Health Organization (WHO), we conducted a retrospective, observational, pharmacovigilance study of melatonin between January 1996 and September 2022. Disproportionality analysis was conducted using two comparator settings: all other drugs and other sleep medications. We used multivariable logistic regression to estimate reporting odds ratios (RORs) with 95% confidence intervals (CIs) to compare the frequencies of AEs reporting between melatonin and each comparator setting. Furthermore, we assessed adverse events of special interests (AESIs) that could potentially be associated with melatonin. Signals were identified when the following criteria were met: cases ≥3, x2 ≥ 4, IC025 ≥ 0, and the lower end of the 95% CI of ROR > 2. These signals were then compared with the AE information on the drug labels provided by regulatory bodies. A total of 35 479 AE reports associated with melatonin were identified, with a higher proportion of reports from females (57.1%) and individuals aged 45-64 years (20.8%). We identified 21 AEs that were commonly detected as safety signals in the disproportionality analyses, including tic, educational problems, disturbance in social behavior, body temperature fluctuation, and growth retardation. In AESI analyses, accidents and injuries (adjusted ROR 2.97; 95% CI, 2.80-3.16), fall (2.24; 2.12-2.37), nightmare (4.90; 4.37-5.49), and abnormal dreams (3.68; 3.19-4.25) were detected as a signal of melatonin when compared to all other drugs, whereas those signals were not detected when compared to other sleep medications. In this pharmacovigilance study, exogenous melatonin showed safety profiles comparable to other sleep medications. However, several unexpected potential safety signals were identified, underscoring the need for further investigation at the population level.

Exogenous Melatonin Use in University Students: A Cross-Sectional Survey

To assess the prevalence of melatonin use and its perceived benefits among university students in different specialties in Saudi Arabia, a cross-sectional survey was conducted between March and June 2023. Data about demographics, time of melatonin use, perceived reasons for exogenous melatonin use, melatonin use in relation to exam periods, perceived safety, and adverse effects was gathered. Of 380 students, ~52% reported using exogenous melatonin for sleep disorders. Most participants reported using melatonin during and after exam periods. Additionally, several (n = 157; 75.4%) believed that its use was safe. The predominant use patterns were daily and as needed, and this study observed a higher rate of use compared with previous studies in Saudi Arabia. The most frequently reported adverse effect was headache (n = 36; 37.5%). A significant number of undergraduate male students in health specialties used melatonin. A high rate of melatonin use was noted during exam periods, which was attributed to sleep deprivation. Additionally, a significant number of students from private universities reported using exogenous melatonin. Melatonin use is common among university students. Future research should use a reliable psychometric measure to test its effect on university students' sleep quality and quantity.

Sirtuins mediate mitochondrial quality control mechanisms: a novel therapeutic target for osteoporosis

Mitochondria plays a role in cell differentiation and apoptosis processes. Maintaining mitochondrial function is critical, and this involves various aspects of mitochondrial quality control such as protein homeostasis, biogenesis, dynamics, and mitophagy. Osteoporosis, a metabolic bone disorder, primarily arises from two factors: the dysregulation between lipogenic and osteogenic differentiation of aging bone marrow mesenchymal stem cells, and the imbalance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. Mitochondrial quality control has the potential to mitigate or even reverse the effects. Among the Sirtuin family, consisting of seven Sirtuins (SIRT1-7), SIRT1-SIRT6 play a crucial role in maintaining mitochondrial quality control. Additionally, SIRT1, SIRT3, SIRT6, and SIRT7 are directly involved in normal bone development and homeostasis by modulating bone cells. However, the precise mechanism by which these Sirtuins exert their effects remains unclear. This article reviews the impact of various aspects of mitochondrial quality control on osteoporosis, focusing on how SIRT1, SIRT3, and SIRT6 can improve osteoporosis by regulating mitochondrial protein homeostasis, biogenesis, and mitophagy. Furthermore, we provide an overview of the current state of clinical and preclinical drugs that can activate Sirtuins to improve osteoporosis. Specific Sirtuin-activating compounds are effective, but further studies are needed. The findings of this study may offer valuable insights for future research on osteoporosis and the development of clinical prevention and therapeutic target strategies.

Influence of Acute Melatonin Administration on Human Physical Performance: A Systematic Review

CONTEXT

Melatonin is an ancient molecule with a wide range of functions in mammals, such as antioxidant, anti-inflammatory, and hypothermic effects among others. However, the influence of acute melatonin administration on human physical performance is debatable.

OBJECTIVE

To summarize available data from controlled trials about the effects of acute melatonin administration on human physical performance, especially with respect to strength, power, speed, and short- and long-term continuous exercise.

DATA SOURCES

A systematic search of the PubMed, Web of Science, Scopus, Embase, and Cochrane databases up to December 10, 2021, was conducted using specified keywords and Boolean operators ("melatonin" AND "exercise OR circuit-based exercise OR plyometric exercise OR exercise tolerance OR exercise test").

STUDY SELECTION

Only controlled studies in the English language and with humans were accepted.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 1.

DATA EXTRACTION

Participants' characteristics (sex, age, body mass, height and fat percentage), melatonin dose and administration time, and outcomes from the performance trial were extracted.

RESULTS

A total of 10 studies were identified after the screening process. Overall, melatonin did not change speed or short-term continuous exercise performances. However, in relation to strength and power, the results are debatable since 5 articles showed no difference, while another 2 pointed to a decrease in performance. In terms of performance improvement, only 1 study reported an increase in balance and another in long-term continuous exercise performance in nonathletes, with no advantage found for athletes.

CONCLUSION

Melatonin did not cause any significant change in strength, speed, power, and short-term continuous exercise performances. In fact, it led to reduced strength and power performances in specific tests. On the other hand, melatonin seems to have improved balance and long-term continuous exercise performance, at least in nonathletes. More investigations are required to corroborate these findings.

An online survey among general pediatricians on melatonin use in children with chronic insomnia

OBJECTIVES

Although melatonin (MLT) is the molecule most used by pediatricians for sleep problems, scarce evidence exists on its use in healthy pediatric population. The objective of this study was to describe MLT use by Italian pediatricians in healthy children with chronic insomnia.

STUDY DESIGN

A cross-sectional open survey was administered to Italian pediatricians, between June and November 2022, collecting information about their use of MLT in healthy children: age range of patients, dosages used, time of administration, duration of treatment, association with other treatments, perceived efficacy, and side effects. Data were reported as frequencies with their respective 95% confidence intervals. Chi-square statistics assessed significant differences between pediatricians who had training in pediatric sleep and those who did not.

RESULTS

Among 428 respondents, 97.4% of pediatricians used MLT; 87.3% of them prescribed MLT in children aged 1-2 years, 62.1% in 2-5 years and 42.5% in 10-18 years. 84.9% of them suggested to take MLT 30 min before bedtime. 37.9% indicated to continue treatment for one month, 30.2% for 2-3 months. 74.1% of pediatricians usually prescribed MLT 1 mg/day. The most frequent treatment associated with MLT was sleep hygiene (85.4%). Almost all pediatricians found MLT effective in reducing difficulties falling asleep. Only 3.2% of them reported mild side effects.

CONCLUSIONS

MLT is widely prescribed by Italian pediatricians, but no consensus exists about its use in typically developing children. There is a need for clear guidelines to optimize the use of MLT in healthy children.

Potential of melatonin to reverse epigenetic aberrations in oral cancer: new findings

It is now an accepted principle that epigenetic alterations cause cellular dyshomeostasis and functional changes, both of which are essential for the initiation and completion of the tumor cycle. Oral carcinogenesis is no exception in this regard, as most of the tumors in the different subsites of the oral cavity arise from the cross-reaction between (epi)genetic inheritance and the huge challenge of environmental stressors. Currently, the biochemical machinery is put at the service of the tumor program, halting the cell cycle, triggering uncontrolled proliferation, driving angiogenesis and resistance to apoptosis, until the archetypes of the tumor phenotype are reached. Melatonin has the ability to dynamically affect the epigenetic code. It has become accepted that melatonin can reverse (epi)genetic aberrations present in oral and other cancers, suggesting the possibility of enhancing the oncostatic capacity of standard multimodal treatments by incorporating this indolamine as an adjuvant. First steps in this direction confirm the potential of melatonin as a countermeasure to mitigate the detrimental side effects of conventional first-line radiochemotherapy. This single effect could produce synergies of extraordinary clinical importance, allowing doses to be increased and treatments not to be interrupted, ultimately improving patients' quality of life and prognosis. Motivated by the urgency of improving the medical management of oral cancer, many authors advocate moving from in vitro and preclinical research, where the bulk of melatonin cancer research is concentrated, to systematic randomized clinical trials on large cohorts. Recognizing the challenge to improve the clinical management of cancer, our motivation is to encourage comprehensive and robust research to reveal the clinical potential of melatonin in oral cancer control. To improve the outcome and quality of life of patients with oral cancer, here we provide the latest evidence of the oncolytic activity that melatonin can achieve by manipulating epigenetic patterns in oronasopharyngeal tissue.

Melatonin loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles reduce inflammation, inhibit apoptosis and protect rat's liver from the hazardous effects of CCL4

Liver is an important organ that carries out major important functions including the detoxification of harmful chemicals. Numerous studies have lately focused on the impact of various substances, such as chemical pollutants and pharmaceutical drugs, on the liver. Melatonin (Mel) has been reported for the protection against liver injury. In order to enhance Mel therapeutic benefits and prevent any potential negative effects, Mel has to be delivered to the injured liver. Therefore, the goal of the current investigation was to create Mel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (Mel-PLGA NPs) to alleviate carbon tetrachloride (CCL4)-induced liver damage in male Sprague Dawley rats. The prepared Mel-PLGA NPs were physically characterized to determine its size and charge. Moreover, Mel-PLGA NPs were examined, in vitro, to determine its antioxidant, anticoagulant, anti-inflammatory and cytotoxicity effects before being used in vivo. The effect of NPs on liver injury was evaluated through biochemical, immunological, histopathological examination and flow cytometry technique. Mel-PLGA NPs were smooth and spherical with no signs of aggregation and have in vitro antioxidant, anti-inflammatory and anticoagulant effects. NPs varied in size from 87 to 96 nm in transmission electron microscope images, while their hydrodynamic diameter was 41 nm and their zeta potential was -6 mV. Mel-PLGA NPs had encapsulation efficiency (EE%) and drug loading (DL%) of 59.9 and 12.5%, respectively. Treatment with Mel-PLGA NPs ameliorated all histopathological changes, in liver sections, that resulted from CCL4 administration; where, liver sections of treated groups were similar to those of healthy control GI. NPs administration were superior to free Mel and reversed the elevated levels of liver function enzymes, inflammatory cytokines and matrix metalloproteinases to their normal levels. Moreover, liver sections of groups treated with NPs showed negative immunostaining for nuclear factor-κB (NF-κB) and C-reactive protein indicating their anti-inflammatory behavior. Mel-PLGA NPs significantly protected liver from the toxicity of CCL4. The effective dose of NPs was 5 mg/kg indicating a reduction in the required Mel dose and its associated adverse effects.

Melatonin, a natural antioxidant therapy in spinal cord injury

Spinal cord injury (SCI) is a sudden onset of disruption to the spinal neural tissue, leading to loss of motor control and sensory function of the body. Oxidative stress is considered a hallmark in SCI followed by a series of events, including inflammation and cellular apoptosis. Melatonin was originally discovered as a hormone produced by the pineal gland. The subcellular localization of melatonin has been identified in mitochondria, exhibiting specific onsite protection to excess mitochondrial reactive oxygen species and working as an antioxidant in diseases. The recent discovery regarding the molecular basis of ligand selectivity for melatonin receptors and the constant efforts on finding synthetic melatonin alternatives have drawn researchers' attention back to melatonin. This review outlines the application of melatonin in SCI, including 1) the relationship between the melatonin rhythm and SCI in clinic; 2) the neuroprotective role of melatonin in experimental traumatic and ischemia/reperfusion SCI, i.e., exhibiting anti-oxidative, anti-inflammatory, and anti-apoptosis effects, facilitating the integrity of the blood-spinal cord barrier, ameliorating edema, preventing neural death, reducing scar formation, and promoting axon regeneration and neuroplasticity; 3) protecting gut microbiota and peripheral organs; 4) synergizing with drugs, rehabilitation training, stem cell therapy, and biomedical material engineering; and 5) the potential side effects. This comprehensive review provides new insights on melatonin as a natural antioxidant therapy in facilitating rehabilitation in SCI.

The effects of sodium butyrate supplementation on the expression levels of PGC-1α, PPARα, and UCP-1 genes, serum level of GLP-1, metabolic parameters, and anthropometric indices in obese individuals on weight loss diet: a study protocol for a triple-blind, randomized, placebo-controlled clinical trial

BACKGROUND

Obesity is a multifaceted disease characterized by an abnormal accumulation of adipose tissue. Growing evidence has proposed microbiota-derived metabolites as a potential factor in the pathophysiology of obesity and related metabolic conditions over the last decade. As one of the essential metabolites, butyrate affects several host cellular mechanisms related to appetite sensations and weight control. However, the effects of butyrate on obesity in humans have yet to be studied. Thus, the present study was aimed to evaluate the effects of sodium butyrate (SB) supplementation on the expression levels of peroxisome proliferator activated-receptor (PPAR) gamma coactivator-1α (PGC-1α), PPARα and uncoupling protein 1 (UCP1) genes, serum level of glucagon-like peptide (GLP1), and metabolic parameters, as well as anthropometric indices in obese individuals on a weight loss diet.

METHODS

This triple-blind randomized controlled trial (RCT) will include 50 eligible obese subjects aged between 18 and 60 years. Participants will be randomly assigned into two groups: 8 weeks of SB (600 mg/day) + hypo-caloric diet or placebo (600 mg/day) + hypo-caloric diet. At weeks 0 and 8, distinct objectives will be pursued: (1) PGC-1α, PPARα, and UCP1 genes expression will be evaluated by real-time polymerase chain reaction; (2) biochemical parameters will be assayed using enzymatic methods; and (3) insulin and GLP1 serum level will be assessed by enzyme-linked immunosorbent assay kit.

DISCUSSION

New evidence from this trial may help fill the knowledge gap in this realm and facilitate multi-center clinical trials with a substantially larger sample size.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials: IRCT20190303042905N2 . Registered on 31 January 2021.

The short-term and long-term adverse effects of melatonin treatment in children and adolescents: a systematic review and GRADE assessment

Background

Currently, melatonin is used to treat children and adolescents with insomnia without knowing the full extent of the short-term and long-term consequences. Our aim was to provide clinicians and guideline panels with a systematic assessment of serious-and non-serious adverse events seen in continuation of melatonin treatment and the impact on pubertal development and bone health following long-term administration in children and adolescents with chronic insomnia.

Methods

We searched PubMed, Embase, Cinahl and PsycINFO via Ovid, up to March 17, 2023, for studies on melatonin treatment among children and adolescents (aged 5-20 years) with chronic insomnia. The language was restricted to English, Danish, Norwegian, and Swedish. Outcomes were non-serious adverse events and serious adverse events assessed 2-4 weeks after initiating treatment and pubertal development and bone health, with no restriction on definition or time of measurement. Observational studies were included for the assessment of long-term outcomes, and serious and non-serious adverse events were assessed via randomised studies. The certainty of the evidence was assessed using Grades of Recommendation, Assessment, Development and Evaluation (GRADE). The protocol is registered with the Danish Health Authority.

Findings

We identified 22 randomised studies with 1350 patients reporting on serious-and non-serious adverse events and four observational studies with a total of 105 patients reporting on pubertal development. Melatonin was not associated with serious adverse events, yet the number of patients experiencing non-serious adverse events was increased (Relative risk 1.56, 95% CI 1.01-2.43, 17 studies, I² = 47%). Three studies reported little or no influence on pubertal development following 2-4 years of treatment, whereas one study registered a potential delay following longer treatment durations (>7 years). These findings need further evaluation due to several methodological limitations.

Interpretation

Children who use melatonin are likely to experience non-serious adverse events, yet the actual extent to which melatonin leads to non-serious adverse events and the long-term consequences remain uncertain. This major gap of knowledge on safety calls for caution against complacent use of melatonin in children and adolescents with chronic insomnia and for more research to inform clinicians and guideline panels on this key issue.

Funding

The Danish Health Authority. The Parker Institute, Bispebjerg and Frederiksberg Hospital, supported by the Oak Foundation.

Therapeutic effect of melatonin-loaded chitosan/lecithin nanoparticles on hyperglycemia and pancreatic beta cells regeneration in streptozotocin-induced diabetic rats

Nanotechnology is used to overcome fundamental flaws in today's marketed pharmaceuticals that obstruct therapy, like restricted solubility and quick release of drugs into the bloodstream. In both human and animal researches, melatonin was demonstrated to regulate glucose levels. Despite the fact that melatonin is quickly transported through the mucosa, its sensitivity to be oxidized creates a difficulty in achieving the required dose. Additionally, due to its variable absorption and poor oral bioavailability necessitates the development of alternative delivery methods. The study aimed to synthesize melatonin loaded chitosan/lecithin (Mel-C/L) nanoparticles to be assessed in the treatment of streptozotocin (STZ)-induced diabetes in rats. The antioxidant, anti-inflammatory, and cytotoxicity properties of nanoparticles were estimated to determine the safety of manufactured nanoparticles for in vivo studies. In addition, Mel-C/L nanoparticles were administered to rats for eight weeks after inducing hyperglycemia. The therapeutic effect of Mel-C/L nanoparticles was assessed in all experimental groups by detecting insulin and blood glucose levels; observing improvements in liver and kidney functions as well as histological and immunohistochemical evaluation of rats' pancreatic sections. The results proved that Mel-C/L nanoparticles showed remarkable anti-inflammatory, anti-coagulant, and anti-oxidant effects, in addition to its efficiency in reducing blood glucose levels of STZ-induced diabetic rats and great ability to promote the regeneration of pancreatic beta (β)-cells. Furthermore, Mel-C/L nanoparticles elevated the insulin level; and decreased the elevated levels of urea, creatinine and cholesterol. In conclusion, nanoparticles application decreased the administrated melatonin dose that in turn can diminish the side effects of free melatonin administration.

Therapeutic Potential of Melatonin Counteracting Chemotherapy-Induced Toxicity in Breast Cancer Patients: A Systematic Review

The purpose of this systematic review is to provide an overview of the existing knowledge on the therapeutic potential of melatonin to counteract the undesirable effects of chemotherapy in breast cancer patients. To this aim, we summarized and critically reviewed preclinical- and clinical-related evidence according to the PRISMA guidelines. Additionally, we developed an extrapolation of melatonin doses in animal studies to the human equivalent doses (HEDs) for randomized clinical trials (RCTs) with breast cancer patients. For the revision, 341 primary records were screened, which were reduced to 8 selected RCTs that met the inclusion criteria. We assembled the evidence drawn from these studies by analyzing the remaining gaps and treatment efficacy and suggested future translational research and clinical trials. Overall, the selected RCTs allow us to conclude that melatonin combined with standard chemotherapy lines would derive, at least, a better quality of life for breast cancer patients. Moreover, regular doses of 20 mg/day seemed to increase partial response and 1-year survival rates. Accordingly, this systematic review leads us to draw attention to the need for more RCTs to provide a comprehensive view of the promising actions of melatonin in breast cancer and, given the safety profile of this molecule, adequate translational doses should be established in further RCTs.

Melatonin and TGF-β-Mediated Release of Extracellular Vesicles

The immune system, unlike other systems, must be flexible and able to "adapt" to fully cope with lurking dangers. The transition from intracorporeal balance to homeostasis disruption is associated with activation of inflammatory signaling pathways, which causes modulation of the immunology response. Chemotactic cytokines, signaling molecules, and extracellular vesicles act as critical mediators of inflammation and participate in intercellular communication, conditioning the immune system's proper response. Among the well-known cytokines allowing for the development and proper functioning of the immune system by mediating cell survival and cell-death-inducing signaling, the tumor necrosis factor α (TNF-α) and transforming growth factor β (TGF-β) are noteworthy. The high bloodstream concentration of those pleiotropic cytokines can be characterized by anti- and pro-inflammatory activity, considering the powerful anti-inflammatory and anti-oxidative stress capabilities of TGF-β known from the literature. Together with the chemokines, the immune system response is also influenced by biologically active chemicals, such as melatonin. The enhanced cellular communication shows the relationship between the TGF-β signaling pathway and the extracellular vesicles (EVs) secreted under the influence of melatonin. This review outlines the findings on melatonin activity on TGF-β-dependent inflammatory response regulation in cell-to-cell communication leading to secretion of the different EV populations.

Melatonin versus Sleep Deprivation for Sleep Induction in Nap Electroencephalography: Protocol for a Prospective Randomized Crossover Trial in Children and Young Adults with Epilepsy

Electroencephalography (EEG) continues to be a pivotal investigation in children with epilepsy, providing diagnostic evidence and supporting syndromic classification. In the pediatric population, electroencephalographic recordings are frequently performed during sleep, since this procedure reduces the number of artifacts and activates epileptiform abnormalities. To date, no shared guidelines are available for sleep induction in EEG. Among the interventions used in the clinical setting, melatonin and sleep deprivation represent the most used methods. The main purpose of this study is to test the non-inferiority of 3–5 mg melatonin versus sleep deprivation in achieving sleep in nap electroencephalography in children and young adult patients with epilepsy. To test non-inferiority, a randomized crossover trial is proposed where 30 patients will be randomized to receive 3–5 mg melatonin or sleep deprivation. Each enrolled subject will perform EEG recordings during sleep in the early afternoon for a total of 60 EEGs. In the melatonin group, the study drug will be administered a single oral dose 30 min prior to the EEG recording. In the sleep deprivation group, parents will be required to subject the child to sleep deprivation the night before registration. Urinary and salivary concentrations of melatonin and of its main metabolite 6-hydroxymelatonin will be determined by using a validated LC-MS method. The present protocol aims to offer a standardized protocol for sleep induction to be applied to EEG recordings in those of pediatric age. In addition, melatonin metabolism and elimination will be characterized and its potential interference in interictal abnormalities will be assessed.

Effects of Melatonin Supplementation on Sleep Quality in Breast Cancer Patients: A Systematic Review and Meta-Analysis

Evidence on the effectiveness of melatonin in breast cancer patients suffering from sleep disturbances is contradictory, and there have been no meta-analyses on its use in humans with breast cancer. This study investigated the melatonin supplementation effectiveness in alleviating sleep disturbances in breast cancer patients. We searched Embase, PubMed, MEDLINE, CINAHL, Cochrane Library, Google Scholar, and Clinical trial.org databases for relevant reports by following PRISMA guidelines and collected clinical experimental studies of melatonin supplementation in breast cancer patients. Breast cancer for the population, melatonin supplementation for intervention, including sleep indicator, cancer treatment-related symptoms for outcomes, and clinical trial for humans were the searched keywords. Among the 1917 identified records, duplicates and irrelevant articles were excluded. Among the 48 full-text articles assessed, 10 studies met the criteria for inclusion in a systematic review, and five studies had sleep-related indicators and were included in the meta-analysis after quality assessment. The estimated average effect size (Hedges' g) was -0.79 (p < 0.001) in a random-effects model, thus indicating that melatonin supplementation had a moderate effect in ameliorating sleep quality in breast cancer patients. Pooled data from studies on melatonin supplementation indicate that melatonin administration may alleviate sleep problems related to treatments in breast cancer patients.

The Utility of Melatonin for the Treatment of Sleep Disturbance After Traumatic Brain Injury: A Scoping Review

OBJECTIVE

To investigate the utility of melatonin supplementation as a treatment option for individuals with sleep disturbance after traumatic brain injury (TBI).

DATA SOURCES

A systematic search was conducted in 6 electronic databases (Medline, AMED, CINAHL, Embase, Scopus, and SPORTDiscus) from earliest records to April 2022.

STUDY SELECTION

Studies were eligible for inclusion if they met the following criteria: a) human participants with sleep disturbance after TBI, b) melatonin or melatonergic agent used as an intervention to treat sleep disturbance, and c) outcomes of melatonin administration reported. All TBI severity types (mild, moderate, and severe) were eligible. The initial search retrieved a total of 595 articles, with 9 studies meeting the eligibility criteria.

DATA EXTRACTION

Two reviewers independently extracted data from eligible studies and assessed methodological quality. Extracted data consisted of participant and injury characteristics, melatonin interventional properties, and sleep outcome. Methodological quality was assessed via the Downs and Black checklist.

DATA SYNTHESIS

A total of 251 participants with TBI-induced sleep disturbance (mean age range: 14.0-42.5 years) were included. Melatonin, Circadin (prolonged-release melatonin), or Ramelteon (melatonin receptor agonist) were administered. Dosages and intervention duration ranged from 2 to 10 mg and 3 to 12 weeks, respectively. Eight out of 9 studies reported positive outcomes after melatonin treatment. Significant improvements in subjective sleep quality, objective sleep efficiency, and total sleep time were found with melatonin. Reductions in self-reported fatigue, anxiety, and depressive symptoms were also observed with melatonin treatment. No serious adverse events were reported after melatonin administration.

CONCLUSION

Melatonin has good tolerability after short-term use and the potential to be a therapeutic agent for those with sleep disturbance after TBI. Melatonin was shown to be beneficial to sleep quality, sleep duration, and sleep efficiency. Additional clinically relevant outcomes of improved mental health suggest that melatonin use may be a promising treatment option for individuals experiencing co-occurring disorders of mood and sleep disturbance post-injury.

Current Insights into the Risks of Using Melatonin as a Treatment for Sleep Disorders in Older Adults

Exogenous melatonin is commonly used for sleep disorders in older adults, and its use is increasing over time. It appears to have modest efficacy in treating insomnia and circadian rhythm sleep-wake disorders. Melatonin is commonly perceived to be a safe alternative to other hypnotics and is available without prescription in some jurisdictions. New evidence suggests that endogenous melatonin has pleomorphic effects on multiple organ systems, many of which are poorly understood. This narrative review summarizes the current evidence regarding the safety of melatonin in older adults (defined by age over 65 years). Melatonin appears to have a favorable safety profile in this population, however there is a dearth of evidence regarding the safety of prolonged use. There are several factors which increase the risk of adverse effects of melatonin in older adults, and these should be taken into consideration when prescribing to this population.

Efficacy and safety of oral melatonin in patients with severe COVID-19: a randomized controlled trial

Patients with COVID-19 have shown melatonin deficiency. We evaluated the efficacy and safety of administration oral melatonin in patients with COVID-19-induced pneumonia. Patients were randomly assigned in a 1:1 ratio to receive melatonin plus standard treatment or standard treatment alone. The primary outcomes were mortality rate and requirement of IMV. The clinical status of patients was recorded at baseline and every day over hospitalization based on seven-category ordinal scale from 1 (discharged) to 7 (death). A total of 226 patients (109 in the melatonin group and 117 in the control group) were enrolled (median age; in melatonin group: 54.60 ± 11.51, in control group: 54.69 ± 13.40). The mortality rate was 67% in the melatonin group and 94% in the control group (OR; 7.75, 95% CI, 3.27-18.35, P < 0.001). The rate of IMV requirement was 51.4% in the melatonin group and 70.9% in the control group, for an OR of 2.31 (95% CI, 1.34-4.00, P < 0.001). The median number of days to hospital discharge was 15 days (13-17) in the melatonin group and 21 days (14-24) in the control group (OR; 5.00, 95% CI, 0.15-9.84, P = 0.026). Time to clinical status improvement by ≥ 2 on the ordinal scale in was 12 days (9-13) in the melatonin group and 16 days (10-19) in the control group (OR; 3.92, 95% CI, 1.69-6.14, P = 0.038). Melatonin significantly improved clinical status with a safe profile in patients with severe COVID-19 pneumonia.

Melatonin for Insomnia in Medical Inpatients: A Narrative Review

In this narrative review, we describe what is known about non-pharmacological and pharmacological treatments for insomnia in medical inpatients, with a focus on melatonin. Hospital-acquired insomnia is common, resulting in shortened total sleep time and more nighttime awakenings. Sleep disturbance has been shown to increase systemic inflammation, pain, and the likelihood of developing delirium in hospital. Treatment for insomnia includes both non-pharmacological and pharmacological interventions, the latter of which requires careful consideration of risks and benefits given the known adverse effects. Though benzodiazepines and non-benzodiazepine benzodiazepine receptor agonists are commonly prescribed (i.e., sedative-hypnotics), they are relatively contraindicated for patients over the age of 65 due to the risk of increased falls, cognitive decline, and potential for withdrawal symptoms after long-term use. Exogenous melatonin has a comparatively low likelihood of adverse effects and drug-drug interactions and is at least as effective as other sedative-hypnotics. Though more research is needed on both its effectiveness and relative safety for inpatients, small doses of melatonin before bedtime may be an appropriate choice for inpatients when insomnia persists despite non-pharmacological interventions.

Adverse events in long-term studies of exogenous melatonin

INTRODUCTION

Exogenous melatonin is regulated as a drug in the UK and EU but is available as an over-the-counter dietary supplement in the US and Canada. In the last 15 years, melatonin use has increased rapidly in many countries, in particular, in children and adolescents who frequently have many years of continuous exposure. Despite this, the potential risks associated with extended use continue to be unclear, and there remains a lack of systematically assessed safety data from long-term prospective trials.

AREAS COVERED

This review focuses on adverse event data reported in long-term (≥6 months) prospective trials of melatonin.

METHODS

The Embase and Medline electronic databases were searched from inception to 12 September 2022 for long-term studies of melatonin, in which adverse events were systematically monitored and reported.

EXPERT OPINION

Although the reported frequency of possible adverse events associated with long-term melatonin use is low and few clinically significant adverse events have been reported, the scarcity of data from double-blind randomized placebo-controlled trials should caution against complacency. Ideally, analysis of data from large well-established research databases should be conducted to provide good quality evidence on which to base a more rigorous evaluation of the safety profile.

Melatonin Treatment for Pediatric Patients with Insomnia: Is There a Place for It?

Sleep is a vital physiological function that is impaired in ranges from 10% in the typically developing pediatric population to over 80% in populations of children with neurodevelopmental disorders and/or psychiatric comorbidities. Pediatric insomnia disorder is an increasing public health concern given its negative impact on synaptic plasticity involved in learning and memory consolidation but also on mood regulation, hormonal development and growth, and its significant impact on quality of life of the child, the adolescent and the family. While first-line treatment of pediatric insomnia should include parental education on sleep as well as sleep hygiene measures and behavioural treatment approaches, pharmacological interventions may be necessary if these strategies fail. Melatonin treatment has been increasingly used off-label in pediatric insomnia, given its benign safety profile. This article aims to identify the possible role of melatonin treatment for pediatric insomnia, considering its physiological role in sleep regulation and the differential effects of immediate release (IR) versus prolonged release (PR) melatonin. For the physician dealing with pediatric insomnia, it is particularly important to be able to distinguish treatment rationales implying different dosages and times of treatment intake. Finally, we discuss the benefit-risk ratio for melatonin treatment in different pediatric populations, ranging from the general pediatric population to children with different types of neurodevelopmental disorders, such as autism spectrum disorder or ADHD.

Associations between treatment with melatonin and suicidal behavior: a nationwide cohort study

STUDY OBJECTIVES

Melatonin is often prescribed to patients with sleep disorders who are known to have elevated suicide risks, yet melatonin's association with suicidal behavior remains to be examined. We investigated whether individuals prescribed melatonin had higher rates of suicide and suicide attempts when compared to individuals who were not prescribed this drug, including both those with and without known mental disorders.

METHODS

A cohort design was applied to longitudinal, register data on all persons aged ≥ 10 years in Denmark during 2007-2016. Based on data from the National Prescription Registry, periods of being in treatment with melatonin were defined using information on the number of tablets and the daily defined dose. We calculated incidence rate ratios for suicide and suicide attempts, as identified in register records, comparing those in treatment with melatonin to those not in treatment.

RESULTS

Among 5,798,923 individuals, 10,577 (0.2%) were treated with melatonin (mean treatment length, 50 days) during the study period. Of those, 22 died by suicide and 134 had at least 1 suicide attempt. People in treatment with melatonin had a 4-fold higher rate of suicide (incidence rate ratio, 4.8; 95% CI, 3.0-7.5) and a 5-fold higher rate of suicide attempt (incidence rate ratio, 5.9; 95% CI, 4.4-8.0) than those not in treatment and when adjusting for sex and age group.

CONCLUSIONS

Treatment with melatonin was associated with suicide and suicide attempt. Although there are several possible explanations, attention to suicide risk is particularly warranted for people with mental comorbidity who are in treatment with melatonin.

CITATION

Høier NK, Madsen T, Spira AP, et al. Associations between treatment with melatonin and suicidal behavior: a nationwide cohort study. J Clin Sleep Med. 2022;18(10):2451-2458.

Is Melatonin the "Next Vitamin D"?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements

Melatonin has become a popular dietary supplement, most known as a chronobiotic, and for establishing healthy sleep. Research over the last decade into cancer, Alzheimer's disease, multiple sclerosis, fertility, PCOS, and many other conditions, combined with the COVID-19 pandemic, has led to greater awareness of melatonin because of its ability to act as a potent antioxidant, immune-active agent, and mitochondrial regulator. There are distinct similarities between melatonin and vitamin D in the depth and breadth of their impact on health. Both act as hormones, affect multiple systems through their immune-modulating, anti-inflammatory functions, are found in the skin, and are responsive to sunlight and darkness. In fact, there may be similarities between the widespread concern about vitamin D deficiency as a "sunlight deficiency" and reduced melatonin secretion as a result of "darkness deficiency" from overexposure to artificial blue light. The trend toward greater use of melatonin supplements has resulted in concern about its safety, especially higher doses, long-term use, and application in certain populations (e.g., children). This review aims to evaluate the recent data on melatonin's mechanisms, its clinical uses beyond sleep, safety concerns, and a thorough summary of therapeutic considerations concerning dietary supplementation, including the different formats available (animal, synthetic, and phytomelatonin), dosing, timing, contraindications, and nutrient combinations.

Homo sapiens May Incorporate Daily Acute Cycles of “Conditioning–Deconditioning” to Maintain Musculoskeletal Integrity: Need to Integrate with Biological Clocks and Circadian Rhythm Mediators

Human evolution required adaptation to the boundary conditions of Earth, including 1 g gravity. The bipedal mobility of Homo sapiens in that gravitational field causes ground reaction force (GRF) loading of their lower extremities, influencing the integrity of the tissues of those extremities. However, humans usually experience such loading during the day and then a period of relative unloading at night. Many studies have indicated that loading of tissues and cells of the musculoskeletal (MSK) system can inhibit their responses to biological mediators such as cytokines and growth factors. Such findings raise the possibility that humans use such cycles of acute conditioning and deconditioning of the cells and tissues of the MSK system to elaborate critical mediators and responsiveness in parallel with these cycles, particularly involving GRF loading. However, humans also experience circadian rhythms with the levels of a number of mediators influenced by day/night cycles, as well as various levels of biological clocks. Thus, if responsiveness to MSK-generated mediators also occurs during the unloaded part of the daily cycle, that response must be integrated with circadian variations as well. Furthermore, it is also possible that responsiveness to circadian rhythm mediators may be regulated by MSK tissue loading. This review will examine evidence for the above scenario and postulate how interactions could be both regulated and studied, and how extension of the acute cycles biased towards deconditioning could lead to loss of tissue integrity.

Melatonin: A window into the organ-protective effects of sepsis

Sepsis is an uncontrolled host response to infection. In some cases, it progresses to multi-organ insufficiency, leading to septic shock and increased risk of mortality. Various organ support strategies are currently applied clinically, but they are still inadequate in terms of reducing mortality. Melatonin is a hormone that regulates sleep and wakefulness, and it is associated with a reduced risk of death in patients with sepsis. Evidence suggests that melatonin may help protect organ function from sepsis-related damage. Here, we review information related to the role of melatonin in protecting organ function during sepsis and explore its potential clinical applications, with the aim of providing an effective therapeutic strategy for treating sepsis-induced organ insufficiency.

Developmental and Early Life Origins of Hypertension: Preventive Aspects of Melatonin

Hypertension represents a major disease burden worldwide. Abundant evidence suggests that hypertension can originate in early life. Adverse programming processes can be prevented by early life intervention-namely, reprogramming-to avoid developing chronic diseases later in life. Melatonin is an endogenously produced hormone with a multifaceted biological function. Although melatonin supplementation has shown benefits for human health, less attention has been paid to exploring its reprogramming effects on the early life origins of hypertension. In this review, first, we discuss the physiological roles of melatonin in pregnancy, fetal development, and the regulation of blood pressure. Then, we summarize the epidemiological and experimental evidence for the early life origins of hypertension. This is followed by a description of the animal models used to examine early melatonin therapy as a reprogramming strategy to protect against the early life origins of hypertension. A deeper understanding of the developmental programming of hypertension and recent advances in early melatonin intervention might provide a path forward in reducing the global burden of hypertension.

Use of Melatonin in Cancer Treatment: Where Are We?

Cancer represents a large group of diseases accounting for nearly 10 million deaths each year. Various treatment strategies, including surgical resection combined with chemotherapy, radiotherapy, and immunotherapy, have been applied for cancer treatment. However, the outcomes remain largely unsatisfying. Melatonin, as an endogenous hormone, is associated with the circadian rhythm moderation. Many physiological functions of melatonin besides sleep–wake cycle control have been identified, such as antioxidant, immunomodulation, and anti-inflammation. In recent years, an increasing number of studies have described the anticancer effects of melatonin. This has drawn our attention to the potential usage of melatonin for cancer treatment in the clinical setting, although huge obstacles still exist before its wide clinical administration is accepted. The exact mechanisms behind its anticancer effects remain unclear, and the specific characters impede its in vivo investigation. In this review, we will summarize the latest advances in melatonin studies, including its chemical properties, the possible mechanisms for its anticancer effects, and the ongoing clinical trials. Importantly, challenges for the clinical application of melatonin will be discussed, accompanied with our perspectives on its future development. Finally, obstacles and perspectives of using melatonin for cancer treatment will be proposed. The present article will provide a comprehensive foundation for applying melatonin as a preventive and therapeutic agent for cancer treatment.

The Therapeutic Effect of Exogenous Melatonin on Depressive Symptoms: A Systematic Review and Meta-Analysis

Background

Depression-related mortality and morbidity pose growing public health burdens worldwide. Although the therapeutic effect of exogenous melatonin on depression has been investigated, findings remain inconsistent. We conducted this systematic review and meta-analysis to clarify the effectiveness of melatonin in the treatment of depression, including primary and secondary depression symptoms.

Methods

We searched the online databases of PubMed, EMBASE, and the Cochrane Library for original studies published up to May 2021. We used STATA 14.0 software to synthesize the results of included studies. To evaluate the effectiveness of melatonin, we calculated the standardized mean differences (SMDs) and 95% confidence intervals (CIs) of depression scores between the melatonin and placebo groups.

Results

Our literature search returned 754 publications, among which 19 studies with 1,178 patients (715 women, 463 men; mean age: 56.77 years) met inclusion criteria. Melatonin dosages ranged from 2 to 25 mg per day; treatment durations were between 10 days and 3.5 years. Our synthesized results showed that melatonin was not found significantly beneficial for alleviating depressive symptoms (SMD = -0.17, 95% CI = [-0.38, 0.05]). Subgroup analysis demonstrated that the decrease in depression scores measured with the Beck Depression Inventory (BDI) was significant (SMD = -0.52, 95% CI = [-0.73, -0.31]).

Conclusions

There is very limited evidence for effects of melatonin on depression.

Safety of higher doses of melatonin in adults: A systematic review and meta-analysis

Melatonin is commonly used for sleep and jetlag at low doses. However, there is less documentation on the safety of higher doses, which are being increasingly used for a wide variety of conditions, including more recently COVID-19 prevention and treatment. The aim of this review was to investigate the safety of higher doses of melatonin in adults. Medline, Scopus, Embase and PsycINFO databases from inception until December 2019 with convenience searches until October 2020. Randomised controlled trials investigating high-dose melatonin (≥10 mg) in human adults over 30 years of age were included. Two investigators independently abstracted articles using PRISMA guidelines. Risk of bias was assessed by a committee of three investigators. 79 studies were identified with a total of 3861 participants. Studies included a large range of medical conditions. The meta-analysis was pooled data using a random effects model. The outcomes examined were the number of adverse events (AEs), serious adverse events (SAEs) and withdrawals due to AEs. A total of 29 studies (37%) made no mention of the presence or absence of AEs. Overall, only four studies met the pre-specified low risk of bias criteria for meta-analysis. In that small subset, melatonin did not cause a detectable increase in SAEs (Rate Ratio = 0.88 [0.52, 1.50], p = .64) or withdrawals due to AEs (0.93 [0.24, 3.56], p = .92), but did appear to increase the risk of AEs such as drowsiness, headache and dizziness (1.40 [1.15, 1.69], p < .001). Overall, there has been limited AE reporting from high-dose melatonin studies. Based on this limited evidence, melatonin appears to have a good safety profile. Better safety reporting in future long-term trials is needed to confirm this as our confidence limits were very wide due to the paucity of suitable data.

Effects of exogenous melatonin supplementation on health outcomes: An umbrella review of meta-analyses based on randomized controlled trials

Various melatonin supplementations have been developed to improve health outcomes in various clinical conditions. Thus, we sought to evaluate and summarize the effect of melatonin treatments in clinical settings for health outcomes. We searched PubMed/Medline, Embase, and Cochrane Library from inception to 4 February 2021. We included meta-analyses of randomized controlled trials investigating the melatonin intervention for any health outcome. Based on the different effect sizes of each meta-analysis, we calculated random models' standardized mean differences or risk ratios. We observed robust evidence supported by statistical significance with non-considerable heterogeneity between studies for sleep-related problems, cancer, surgical patients, and pregnant women. Patients with sleep disorder, sleep onset latency (SMD 0.33, 95% CI: 0.10 - 0.56, P < 0.01) were significantly improved whereas no clear evidence was shown with sleep efficiency (1.10, 95% CI: -0.26 to 2.45). The first analgesic requirement time (SMD 5.81, 95% CI: 2.57-9.05, P < 0.001) of surgical patients was distinctly improved. Female patients under artificial reproductive technologies had significant increase in the top-quality embryos (SMD 0.53, 95% CI: 0.27 - 0.79, P < 0.001), but no statistically clear evidence was found in the live birth rate (SMD 1.20, 95% CI: 0.83 - 1.72). Survival at one year (RR 1.90, 95% CI: 1.28 - 2.83, P < 0.005) significantly increased with cancer patients. Research on melatonin interventions to treat clinical symptoms and sleep problems among diverse health conditions was identified and provided considerable evidence. Future well-designed randomized clinical trials of high quality and subgroup quantitative analyses are essential.

What do we really know about the safety and efficacy of melatonin for sleep disorders?

Melatonin is a hormonal product of the pineal gland, a fact that is often forgotten. Instead it is promoted as a dietary supplement that will overcome insomnia, as an antioxidant and as a prescription only drug in most countries outside the United States of America and Canada. The aim of this review is to step back and highlight what we know about melatonin following its discovery 60 years ago. What is the role of endogenous melatonin; what does melatonin do to sleep, body temperature, circadian rhythms, the cardiovascular system, reproductive system, endocrine system and metabolism when administered to healthy subjects? When used as a drug/dietary supplement, what safety studies have been conducted? Can we really say melatonin is safe when it has not been systematically studied and many studies show interactions with a wide range of physiological processes? Finally the results of studies investigating the efficacy of melatonin as a drug to alleviate insomnia are critically evaluated. In summary, melatonin is an endogenous pineal gland hormone with specific physiological functions in animals and humans, with its primary role in humans to maintain synchrony of sleep with the day/night cycle. When administered as a drug it affects a wide range of physiological systems and has clinically important drug interactions. With respect to efficacy for treating sleep disorders, melatonin can advance the time of sleep onset but the effect is modest and variable. In children with neurodevelopmental disabilities melatonin appears to have the greatest impact on sleep onset but little effect on sleep efficiency.

Potential and Possible Therapeutic Effects of Melatonin on SARS-CoV-2 Infection

The absence of effective drugs for COVID-19 prevention and treatment requires the search for new candidates among approved medicines. Fundamental studies and clinical observations allow us to approach an understanding of the mechanisms of damage and protection from exposure to SARS-CoV-2, to identify possible points of application for pharmacological interventions. In this review we presented studies on the anti-inflammatory, antioxidant, and immunotropic properties of melatonin. We have attempted to present scientifically proven mechanisms of action for the potential therapeutic use of melatonin during SARS-CoV-2 infection. A wide range of pharmacological properties allows its inclusion as an effective addition to the methods of prevention and treatment of COVID-19.

Melatonin's Benefits and Risks as a Therapy for Sleep Disturbances in the Elderly: Current Insights

Aging is accompanied by circadian changes, including disruptive alterations in the sleep/wake cycle, as well as the beginning of low-degree inflammation ("inflammaging"), a scenario that leads to several chronic illnesses, including cancer, and metabolic, cardiovascular, and neurological dysfunctions. As a result, any effective approach to healthy aging must consider both the correction of circadian disturbance and the control of low-grade inflammation. One of the most important prerequisites for healthy aging is the preservation of robust circadian rhythmicity (particularly of the sleep/wake cycle). Sleep disturbance disrupts various activities in the central nervous system, including waste molecule elimination. Melatonin is a chemical with extraordinary phylogenetic conservation found in all known aerobic creatures whose alteration plays an important role in sleep changes with aging. Every day, the late afternoon/nocturnal surge in pineal melatonin helps to synchronize both the central circadian pacemaker found in the hypothalamic suprachiasmatic nuclei (SCN) and a plethora of peripheral cellular circadian clocks. Melatonin is an example of an endogenous chronobiotic substance that can influence the timing and amplitude of circadian rhythms. Moreover, melatonin is also an excellent anti-inflammatory agent, buffering free radicals, down-regulating proinflammatory cytokines, and reducing insulin resistance, among other things. We present both scientific and clinical evidence that melatonin is a safe drug for treating sleep disturbances in the elderly.