The use and misuse of exogenous melatonin in the treatment of sleep disorders

Systematic review of melatonin in cerebral ischemia-reperfusion injury: critical role and therapeutic opportunities

Cerebral ischemia-reperfusion (I/R) injury is the predominant causes for the poor prognosis of ischemic stroke patients after reperfusion therapy. Currently, potent therapeutic interventions for cerebral I/R injury are still very limited. Melatonin, an endogenous hormone, was found to be valid in preventing I/R injury in a variety of organs. However, a systematic review covering all neuroprotective effects of melatonin in cerebral I/R injury has not been reported yet. Thus, we perform a comprehensive overview of the influence of melatonin on cerebral I/R injury by collecting all available literature exploring the latent effect of melatonin on cerebral I/R injury as well as ischemic stroke. In this systematic review, we outline the extensive scientific studies and summarize the beneficial functions of melatonin, including reducing infarct volume, decreasing brain edema, improving neurological functions and attenuating blood-brain barrier breakdown, as well as its key protective mechanisms on almost every aspect of cerebral I/R injury, including inhibiting oxidative stress, neuroinflammation, apoptosis, excessive autophagy, glutamate excitotoxicity and mitochondrial dysfunction. Subsequently, we also review the predictive and therapeutic implications of melatonin on ischemic stroke reported in clinical studies. We hope that our systematic review can provide the most comprehensive introduction of current advancements on melatonin in cerebral I/R injury and new insights into personalized diagnosis and treatment of ischemic stroke.

Healthy sleep practices for shift workers: consensus sleep hygiene guidelines using a Delphi methodology

STUDY OBJECTIVES

The unique requirements of shift work, such as sleeping and working at variable times, mean that current sleep hygiene guidelines may be inappropriate for shift workers. Current guidelines may also contradict fatigue management advice (e.g. advising against daytime napping). The present study utilized a Delphi methodology to determine expert opinion regarding the applicability of current guidelines for shift workers, the appropriateness of the term "sleep hygiene," and develop tailored guidelines for shift workers.

METHODS

The research team reviewed current guidelines and existing evidence to draft tailored guidelines. Seventeen individual guidelines, covering sleep scheduling, napping, sleep environment, bedtime routine, substances, light exposure, diet, and exercise were drafted. Experts from sleep, shift work, and occupational health fields (n = 155) were invited to review the draft guidelines using a Delphi methodology. In each round, experts voted on individual guidelines, with 70% agreement considered consensus. Where consensus was not reached, written feedback from experts was discussed and incorporated into subsequent iterations.

RESULTS

Of the experts invited, 68 (44%) agreed to participate, with 55 (35%) completing the third (final) round. Most experts (84%) agreed that tailored guidelines were required for shift workers. Consensus was reached on all guidelines after three rounds. One additional guideline (sleep inertia) and an introductory statement were developed, resulting in a final set of 18 individual guidelines, termed "healthy sleep practices for shift workers."

CONCLUSIONS

This is the first study to develop tailored sleep hygiene guidelines for shift workers. Future research should investigate the acceptability and effectiveness of these guidelines amongst shift workers.

Pharmacists' perspectives and attitudes towards the 2021 down-scheduling of melatonin in Australia using the Theoretical Domains Framework: a mixed-methods study

BACKGROUND

In Australia, prescription melatonin became a 'Pharmacist Only Medicine' for people over 55 with insomnia from June 2021. However, little is known about pharmacists' views on melatonin down-scheduling and perceived impacts on practice.

AIM

To explore Australian community pharmacists' views on and attitudes towards the down-scheduling of melatonin.

METHOD

A convenience sample of community pharmacists and pharmacy interns were recruited. Participants completed a survey capturing demographic and professional practice details, and rated their knowledge, beliefs and attitudes towards melatonin. This was followed by an online semi-structured interview. Interviews were guided by a schedule of questions developed using the Theoretical Domains Framework and explored the perceived role of melatonin, preparation/response to down-scheduling, practice changes and patient interactions. Interviews continued until data saturation and were digitally recorded, transcribed verbatim and analysed using the Framework Approach.

RESULTS

Twenty-four interviews were conducted with community pharmacists (n = 19) and intern pharmacists (n = 5), all practicing in metropolitan areas. Pharmacists/intern pharmacists welcomed the increased accessibility of melatonin for patients. However, pharmacists perceived a disconnect between the guidelines, supply protocols and pack sizes with practice, making it difficult to monitor patient use of melatonin. The miscommunication of eligibility also contributed to patient-pharmacist tension when supply was denied. Importantly, most participants indicated their interest in upskilling their knowledge in melatonin use in sleep, specifically formulation differences and dosage titration.

CONCLUSION

While pharmacists welcomed the down-scheduling of melatonin, several challenges were noted, contributing to pharmacist-patient tensions in practice. Findings highlight the need to refine and unify melatonin supply protocols and amend pack sizes to reflect guideline recommendations as well as better educating the public about the risk-benefits of melatonin.

Neuroprotective effects of melatonin in neurodegenerative and autoimmune central nervous system diseases

The suprachiasmatic nucleus (SCN) in the anterior hypothalamus is the major circadian pacemaker in humans. Melatonin is a key hormone secreted by the pineal gland in response to darkness. Light-induced stimuli are transmitted along the retinohypothalamic tract to the SCN. Activation of the SCN inhibits the production of melatonin by the pineal gland through a complex neural pathway passing through the superior cervical ganglion. Accordingly, when light is unavailable, the pineal gland secretes melatonin. The circadian rhythm modulates sleep-wake cycles as well as many physiological functions of the endocrine system, including core body temperature, pulse rate, oxygen consumption, hormone levels, metabolism, and gastrointestinal function. In neurodegenerative disorders, the sleep-wake cycle is disrupted and circadian regulation is altered, which accelerates disease progression, further disrupting circadian regulation and setting up a vicious cycle. Melatonin plays a critical role in the regulation of circadian rhythms and is a multifunctional pleiotropic agent with broad neuroprotective effects in neurodegenerative disorders, viral or autoimmune diseases, and cancer. In this review, I discuss the neuroprotective functions of melatonin in circadian regulation and its roles in promoting anti-inflammatory activity, enhancing immune system functions, and preventing alterations in glucose metabolism and mitochondrial dysfunction in neurodegenerative disorders and autoimmune central nervous system diseases.

Melatonin in different food samples: Recent update on distribution, bioactivities, pretreatment and analysis techniques

Melatonin (MLT) plays a significant role on maintaining the basic physiological functions and regulating various metabolic processes in plentiful organisms. Recent years have witnessed an increase in MLT's share in global market with its affluent functions. However, the worrisome quality issues and inappropriate or excessive application of MLT take place inevitably. In addition, its photosensitive properties, oxidation, complex substrate concentration and trace levels leave exact detection of MLT doubly difficult. Therefore, it is essential to exploit precise, sensitive and stable extraction and detection methods to resolve above questions. In this study, we reviewed the distribution and bioactivities of MLT and conducted a comprehensive overview of the developments of pretreatment and analysis methods for MLT in food samples since 2010. Commonly used pretreatment methods for MLT include not only traditional techniques, but also novel ones, such as solid-phase extraction, QuEChERS, microextraction by packed sorbent, solid phase microextraction, liquid phase microextraction, and so on. Analysis methods include liquid chromatography coupled with different detectors, GC methods, capillary electrophoresis, sensors, and so on. The advantages and disadvantages of different techniques have been compared and the development tendency was prospected.

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.

Redox Biology of Melatonin: Discriminating Between Circadian and Noncircadian Functions

Melatonin has not only to be seen as a regulator of circadian clocks. In addition to its chronobiotic functions, it displays other actions, especially in cell protection. This includes antioxidant, anti-inflammatory, and mitochondria-protecting effects. Although protection is also modulated by the circadian system, the respective actions of melatonin can be distinguished and differ with regard to dose requirements in therapeutic settings. It is the aim of this article to outline these differences in terms of function, signaling, and dosage. Focus has been placed on both the nexus and the dissecting properties between circadian and noncircadian mechanisms. This has to consider details beyond the classic view of melatonin's role, such as widespread synthesis in extrapineal tissues, formation in mitochondria, effects on the mitochondrial permeability transition pore, and secondary signaling, for example, via upregulation of sirtuins and by regulating noncoding RNAs, especially microRNAs. The relevance of these findings, the differences and connections between circadian and noncircadian functions of melatonin shed light on the regulation of inflammation, including macrophage/microglia polarization, damage-associated molecular patterns, avoidance of cytokine storms, and mitochondrial functions, with numerous consequences to antioxidative protection, that is, aspects of high actuality with regard to deadly viral and bacterial diseases. Antioxid. Redox Signal. 37, 704-725.

The Effects of the Exogenous Melatonin on Shift Work Sleep Disorder in Health Personnel: A Systematic Review

(1) Background: To know the medical documentation related to exogenous melatonin in sleep disorders caused by shift work in health personnel; (2) Methods: Systematic and critical review. Data were obtained by looking up the bibliographic data base: MEDLINE (via Pubmed), Embase, Cochrane Library, Scopus, Web of Science, Latin American and Caribbean literature in Health Sciences (LILACS) and Medicine in Spanish (MEDES). The used terms, as descriptors and text in the title and abstract record fields, were "Health Personnel", "Melatonin" and "Sleep Disorders", Circadian Rhythm, by using the following filters: "Humans", "Adult: 19+ years" and "Clinical Trial". The search update was in December 2021. The documentary quality of the articles was assessed using the CONSORT questionnaire. (3) Results: Having applied the inclusion and exclusion criteria, 10 clinical essays were selected out of 98 retrieved references. CONSORT scores ranged from a minimum of 6.0 to a maximum of 13. 7 with a median of 10.2. According to the SIGN criteria, this review presented "1-"evidence with a grade of recommendation B. The intervention dose via administration of exogenous melatonin ranged between 1 and 10 mg. It was not mentioned whether the route of administration was by fast or slow absorption. The outcomes showed decreased daytime sleepiness, lessened sleep onset latency, diminished night-time awakenings, increased total sleep period and improved daytime attention in the melatonin-treated group; (4) Conclusions: Exogenously administered melatonin is effective in shift worker health personnel that are suffering from sleep disorders, and given its low adverse effects and tolerability, it might be recommended. A great disparity was evidenced in terms of dose, follow-up periods and type of melatonin, small participant population, same age ranges and young age. Therefore, new trials would be needed to amend these observations in order to have full evidence that is able to ensure the efficacy of exogenous melatonin in the studied population.

Melatonergic Receptors (Mt1/Mt2) as a Potential Additional Target of Novel Drugs for Depression

A complex pathogenesis involving several physiological systems is theorized to underline the development of depressive disorders. Depression is accompanied by circadian regulation disruption and interaction with the functioning of both central and peripheral oscillators. Many aspects of melatonin function unite these systems. The use of drugs for circadian rhythm disorders could inspire a potential treatment strategy for depression. Melatonin plays an essential role in the regulation of circadian rhythms. It exerts effect by activating two types of melatonin receptors, type 1A (MT1) and 1B (MT2). These are G-protein-coupled receptors, predominantly located in the central nervous system. MT1/MT2 agonists could be a useful treatment approach according to all three prevalent theories of the pathogenesis of depression involving either monoamines, synaptic remodeling, or immune/inflammatory events. MT1/MT2 receptors can be a potential target for novel antidepressants with impact on concentrations of neurotrophins or neurotransmitters, and reducing levels of pro-inflammatory cytokines. There is an interesting cross-talk mediated via the physical association of melatonin and serotonin receptors into functional heteromers. The antidepressive and neurogenetic effects of MT1/MT2 agonists can also be caused by the inhibition of the acid sphingomyelinase, leading to reduced ceramide, or increasing monoamine oxidase A levels in the hippocampus. Compounds targeting MT1 and MT2 receptors could have potential for new anti-depressants that may improve the quality of therapeutic interventions in treating depression and relieving symptoms. In particular, a combined effect on MT1 and/or MT2 receptors and neurotransmitter systems may be useful, since the normalization of the circadian rhythm through the melatonergic system will probably contribute to improved treatment. In this review, we discuss melatonergic receptors as a potential additional target for novel drugs for depression.

Sleep and chronotype in adults with persistent tic disorders

OBJECTIVE

This study examined sleep disorders and sleep medication use rates, nighttime tics, and sleep and chronotype in relation to tic and co-occurring symptoms in adults with persistent tic disorders (PTDs), including Tourette's disorder (TD).

METHODS

One hundred twenty-five adult internet survey respondents rated sleep history, sleep, chronotype, tic severity, impairment, attention deficit hyperactivity disorder, obsessive-compulsive symptoms, anxiety, depression, and emotional and behavioral dyscontrol.

RESULTS

Bruxism, insomnia, tic-related difficulty falling asleep, and melatonin use were commonly endorsed. Sleep disturbance correlated with impairment, obsessive-compulsive symptoms, and emotional and behavioral dyscontrol. Eveningness correlated with vocal and total tic severity only in TD. Controlling for age and sex, age, impairment, and obsessive-compulsive symptoms predicted sleep disturbance, and age and tic severity predicted chronotype.

CONCLUSIONS

Impairment and obsessive-compulsive symptoms play a role in sleep disturbance in adults with PTDs, and may be intervention targets. Eveningness relates to tic severity, which may suggest the utility of interventions to advance chronotype.

Effect of melatonin in children with neurodevelopmental disabilities and sleep disorders

Objectives:

The aim of this study is to assess the efficacy and side effects of melatonin use in a population of children with neurodevelopmental disabilities who had sleep disorders.

Methods:

This is a cross-sectional study conducted in the pediatric neurology clinic at King Abdulaziz Medical City. A designed questionnaire was given to the parents to inquire about the sleep characteristics of their children before and after using melatonin. The patients' demographic data were collected and different parameters before and after starting melatonin were compared. Categorical variables were summarized and reported in terms of frequency and percent (n%). Continuous variables were reported in terms of mean and standard deviation.

Results:

A total of 23 patients were enrolled in our study, of which 15 (65.22%) were male. The mean age was 5.83 ± 3.07 years. For melatonin dose, 9 (39.13%) received 1 mg, 8 (34.78%) received 2 mg, and 6 (26.09%) received over 3 mg. Regarding melatonin duration of use, 7 (30.43%) received melatonin for 0 to 6 months, 7 (30.43%) received it for 7 to 12 months, and 9 (39.13%) received it for over a year. Significant differences were observed in time taken to fall asleep (P =0.046), the number of times the child woke up at night (P =0.071), total sleep time within 24 hours (P =.011), and time taken to wake up (P =.007), while no significant difference was observed in the number of naps taken during the daytime (P =.801). There were no major side effects reported.

Conclusion:

Melatonin had a significant impact on total sleep time and quality during the pre and post assessment of children with neurodevelopmental disabilities and sleep disorders.

Mechanisms of Melatonin in Obesity: A Review

Obesity and its complications have become a prominent global public health problem that severely threatens human health. Melatonin, originally known as an effective antioxidant, is an endogenous hormone found throughout the body that serves various physiological functions. In recent decades, increasing attention has been paid to its unique function in regulating energy metabolism, especially in glucose and lipid metabolism. Accumulating evidence has established the relationship between melatonin and obesity; nevertheless, not all preclinical and clinical evidence indicates the anti-obesity effect of melatonin, which makes it remain to conclude the clinical effect of melatonin in the fight against obesity. In this review, we have summarized the current knowledge of melatonin in regulating obesity-related symptoms, with emphasis on its underlying mechanisms. The role of melatonin in regulating the lipid profile, adipose tissue, oxidative stress, and inflammation, as well as the interactions of melatonin with the circadian rhythm, gut microbiota, sleep disorder, as well as the α7nAChR, the opioidergic system, and exosomes, make melatonin a promising agent to open new avenues in the intervention of obesity.

Ritmi circadiani e variabili metaboliche

I ritmi circadiani sono influenzati da numerose variabili correlate allo stile di vita, soprattutto in relazione ai ritmi imposti dalla società moderna, e vengono profondamente alterati da diverse condizioni patologiche. La fisiologia circadiana è organizzata in modo complesso e integrato; molti dei fattori che sincronizzano il sistema sono a loro volta influenzati e regolati da diversi assi ormonali. Parallelamente, i disturbi del ritmo circadiano derivano da input non ottimali dei fattori sincronizzanti o da condizioni patologiche, e le conseguenze determinano un impatto significativo in diverse condizioni, quali l’obesità e i disturbi del sonno. Durante l’attuale emergenza COVID-19 sono stati registrati crescenti tassi di alterazioni del sonno, complici la preoccupazione diffusa, un comportamento alimentare alterato e la difficoltà per molti, durante il lockdown, nel mantenere ritmi di vita regolari (Barrea et al. in J Transl Med 18:1–11, 2020). Le misure di intervento che si sono mostrate più promettenti contro la desincronizzazione circadiana sono quelle che agiscono sullo stile di vita, basate sul recupero di un corretto ritmo del sonno, la corretta esposizione alla luce solare, l’idonea distribuzione dei pasti e del timing alimentare e lo svolgimento di un’adeguata attività fisica.

Circadian rhythm as a therapeutic target

The circadian clock evolved in diverse organisms to integrate external environmental changes and internal physiology. The clock endows the host with temporal precision and robust adaptation to the surrounding environment. When circadian rhythms are perturbed or misaligned, as a result of jet lag, shiftwork or other lifestyle factors, adverse health consequences arise, and the risks of diseases such as cancer, cardiovascular diseases or metabolic disorders increase. Although the negative impact of circadian rhythm disruption is now well established, it remains underappreciated how to take advantage of biological timing, or correct it, for health benefits. In this Review, we provide an updated account of the circadian system and highlight several key disease areas with altered circadian signalling. We discuss environmental and lifestyle modifications of circadian rhythm and clock-based therapeutic strategies, including chronotherapy, in which dosing time is deliberately optimized for maximum therapeutic index, and pharmacological agents that target core clock components and proximal regulators. Promising progress in research, disease models and clinical applications should encourage a concerted effort towards a new era of circadian medicine.

Research Hot Spots and Trends on Melatonin From 2000 to 2019

Research on melatonin remains one of the major hot spots in the field of disease treatment, but relevant data are numerous. The purpose of this study was to quantitatively and qualitatively analyze the progress of melatonin research through the method of bibliometrics and to predict hot spots and trends in melatonin research. This study retrieved all the studies on melatonin from 2000 to 2019 in the Web of Science and PubMed and analysed the publishing trends in the literature on a bibliometric online analysis platform and CiteSpace software. The research results were also visually analysed to summarize melatonin research hot spots through gCLUTO and pubMR. The study retrieved a total of 20,351 publications, of which the number of US publications ranked first, accounting for 21.46%, with the greatest impact (centrality = 0.31). The University of Texas Health Science Center at San Antonio and Harvard University had the highest average number of citations at 43.19 and 33.96, respectively. Journal of Pineal Research had the highest average number of citations in 2,993 journals. Professor Reiter made the largest contribution to this area. We further analysed 100 highly cited articles for clinical applications and ongoing related clinical drug trials based on the first hot spot. We systematically analysed melatonin for nearly 20 years while predicting the main research trends in the future, which may provide new directions and ideas for melatonin research. The structure and normal physiological functions of melatonin have been intensively studied in the past few years. And clinical application research and target of melatonin treatment for different diseases and target-based drug design will certainly become the focus of melatonin research.

Expert Opinions and Consensus Recommendations for the Evaluation and Management of Insomnia in Clinical Practice: Joint Statements of Five Italian Scientific Societies

BACKGROUND

Insomnia is the most commonly reported sleep problem in industrialized countries worldwide being present in about 36.8% of the general population. In Italy, such a percentage seems to be even higher. Although insomnia can be an independent disorder, it is most frequently observed as a comorbid condition and may precipitate, exacerbate, or prolong a broad range of comorbid conditions including physical and mental illnesses. Evaluating and targeting insomnia in the Italian clinical practice should be a priority.

METHODS

The present expert options and recommendations development process was based on the RAND/UCLA Appropriateness Method for conceptualizing, designing, and carrying out the appropriateness of procedures for the diagnosis and treatment. Only available options in Italy were taken into considerations.

RESULTS

We evaluated 12 international guidelines and 12 most recent systematic reviews for insomnia evaluation and treatment produced in the last 10 years.

CONCLUSIONS

Our findings suggested that symptoms of insomnia must always be assessed in the Italian clinical practice by evaluating nocturnal and daytime symptoms, comorbid conditions and lifestyle. In a patient with chronic insomnia with and without comorbidity, insomnia treatment should be always initiated. CBT-Insomnia therapy should be the first option accordingly to availability. The choice of the drug should be based on different factors such as type of insomnia, age, comorbidities, and potential side effects. Melatonin 2 mg prolonged release should be the first choice in subjects >55 years. If the choice would be a Z-drug or a short-acting benzodiazepine (in subjects <65 years old) or a sedating antidepressant, the use should be in the short term (≤4 weeks) and then proceeds to tapering under clinical monitoring.

Evaluating a nurse-led sleep support intervention to reduce melatonin prescribing in children and young people

BACKGROUND

Sleep disturbance, often arising from the way parents manage their child's sleep, affects 40% of children and leads to increased demand on clinical services. Children and young people with significant sleep issues can be treated effectively with a supportive approach but are often prescribed the hormone melatonin because of a lack of available support services.

AIM

To understand the effect and clinical implications of a nurse-led sleep support clinic on melatonin prescribing in children and young people.

METHOD

A retrospective case note evaluation was undertaken of a nurse-led sleep support service delivering a bespoke programme and follow-up support to a patient group of 124 children and young people, 104 of whom had co-morbidities.

RESULTS

A total of 78 (63%) patients were successfully discharged without melatonin prescriptions after a median of two face-to-face clinic visits and three telephone calls. Eleven out of 12 patients had not restarted melatonin after 12 months.

CONCLUSION

A nurse-led, non-pharmacological approach to sleep support in children and young people can provide an effective, sustainable alternative to melatonin prescribing. The authors recommend that appropriate sleep support should be administered and the response reviewed before melatonin is prescribed. Investment in sleep services to support this approach is important.