The effects of low-dose 0.5-mg melatonin on the free-running circadian rhythms of blind subjects

Mathematical Analysis of Light-sensitivity Related Challenges in Assessment of the Intrinsic Period of the Human Circadian Pacemaker

Accurate assessment of the intrinsic period of the human circadian pacemaker is essential for a quantitative understanding of how our circadian rhythms are synchronized to exposure to natural and man-made light-dark (LD) cycles. The gold standard method for assessing intrinsic period in humans is forced desynchrony (FD) which assumes that the confounding effect of lights-on assessment of intrinsic period is removed by scheduling sleep-wake and associated dim LD cycles to periods outside the range of entrainment of the circadian pacemaker. However, the observation that the mean period of free-running blind people is longer than the mean period of sighted people assessed by FD (24.50 ± 0.17 h vs 24.15 ± 0.20 h, p < 0.001) appears inconsistent with this assertion. Here, we present a mathematical analysis using a simple parametric model of the circadian pacemaker with a sinusoidal velocity response curve (VRC) describing the effect of light on the speed of the oscillator. The analysis shows that the shorter period in FD may be explained by exquisite sensitivity of the human circadian pacemaker to low light intensities and a VRC with a larger advance region than delay region. The main implication of this analysis, which generates new and testable predictions, is that current quantitative models for predicting how light exposure affects entrainment of the human circadian system may not accurately capture the effect of dim light. The mathematical analysis generates new predictions which can be tested in laboratory experiments. These findings have implications for managing healthy entrainment of human circadian clocks in societies with abundant access to light sources with powerful biological effects.

Short-Wavelength Light-Blocking Filters and Oral Melatonin Administration in Patients With Retinitis Pigmentosa: Protocol for a Randomized Controlled Trial

BACKGROUND

The medical community is beginning to recognize that retinitis pigmentosa (RP), due to its disabling progression, eventually leads to a reduction in the patient´s quality of life, a direct economic impact, and an increase in the burden on the health care system. There is no curative treatment for the origin of the disease, and most of the current interventions fail in reducing the associated negative psychological states, such as anxiety and depression, which lead to increased variability of vision and pose a continuous threat to the patient's independence.

OBJECTIVE

The aim of this study is to assess the effect of oral melatonin (OM) administration alone and combined with short-wavelength light (SWL)-blocking filters on patients with RP and test their effectiveness in improving the level of stress and sleep problems in many of these patients.

METHODS

We have developed a low-cost therapy protocol for patients with RP with sleep disorders and negative psychological stress. Patients will be randomized to receive a combined intervention with SWL-blocking filters and OM, SWL-blocking filters alone, or OM alone. There will also be a nonintervention arm as a control group. This study will be conducted across 2 retinal units in patients with RP with sleep disorders and high perceived stress and anxiety score reports. Patients will be assessed in the preintervention period, weekly during the 4 weeks of intervention, and then at 6 months postintervention. The primary outcomes are the differences in changes from baseline to postintervention in hormone release (α-amylase, cortisol, and melatonin) and sleep quality, as measured with the visual analog scale. Secondary outcome measures include clinical macular changes, as measured with optical coherence tomography and optical coherence tomography angiography; retinal function, as measured using the visual field and best-corrected visual acuity; sleep data collected from personal wearables; and several patient-reported variables, such as self-recorded sleep diaries, quality of life, perceived stress, and functional status.

RESULTS

This project is still a study protocol and has not yet started. Bibliographic research for information for its justification began in 2020, and this working group is currently seeking start-up funding. As soon as we have the necessary means, we will proceed with the registration and organization prior to the preliminary phase.

CONCLUSIONS

In this feasibility randomized clinical controlled trial, we will compare the effects of SWL blocking alone, administration of OM alone, and a combined intervention with both in patients with RP. We present this study so that it may be replicated and incorporated into future studies at other institutions, as well as applied to additional inherited retinal dystrophies. The goal of presenting this protocol is to aid recent efforts in reducing the impact of sleeping disorders and other psychological disorders on the quality of life in patients with RP and recovering their self-autonomy. In addition, the results of this study will represent a significant step toward developing a novel low-cost therapy for patients with RP and validating a novel therapeutic target.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/49196.

Glycemic Variability in Patients with Type 2 Diabetes Mellitus (T2DM): The Role of Melatonin in a Crossover, Double-Blind, Placebo-Controlled, Randomized Study

BACKGROUND

Glycemic variability in patients with type 2 diabetes mellitus (T2DM) may be associated with chronic complications of the disease. Melatonin is a hormone that plays a crucial role in biological rhythms. Previous studies have indicated that individuals with T2DM often exhibit reduced melatonin production. In this study, our objective was to investigate whether nighttime melatonin supplementation could mitigate glycemic variability in these patients.

METHODS

Crossover, double-blind, placebo-controlled, randomized study. A total of 30 patients were enrolled in this study. The study included 15 participants who followed the intervention sequence of placebo (7 days)-washout (7 days)-melatonin (3 mg) (7 days), and another 15 participants who followed the sequence of melatonin (3 mg) (7 days)-washout (7 days)-placebo (7 days). During the final three days of the first and third weeks, the participants measured their pre- and postprandial capillary blood glucose levels. This study was reported according to the CONSORT 2010 statement: extension to randomized crossover trials.

RESULTS

There was a significant absolute difference in the breakfast blood glucose levels (p = 0.016) on Day 7. The use of melatonin determined a greater positive variation between pre- and postprandial glycemia than the placebo. The difference in glycemic amplitude between post-dinner Day 6 and pre-breakfast Day 7 was also significantly higher in the melatonin group (p = 0.032).

CONCLUSIONS

Melatonin increased glycemic variability in individuals with type 2 diabetes mellitus (T2DM). These results can be attributed to the residual daytime effects of melatonin, prospective proximal effects, and damage to the prospective distal effects of exogenous melatonin. Therefore, caution should be exercised when administering melatonin supplementation to patients with T2DM, taking into consideration factors such as dosage, duration of use and genetic considerations.

Melatonin as a Chronobiotic with Sleep-promoting Properties

The use of exogenous melatonin (exo-MEL) as a sleep-promoting drug has been under extensive debate due to the lack of consistency of its described effects. In this study, we conduct a systematic and comprehensive review of the literature on the chronobiotic, sleep-inducing, and overall sleep-promoting properties of exo-MEL. To this aim, we first describe the possible pharmacological mechanisms involved in the sleep-promoting properties and then report the corresponding effects of exo-MEL administration on clinical outcomes in: a) healthy subjects, b) circadian rhythm sleep disorders, c) primary insomnia. Timing of administration and doses of exo-MEL received particular attention in this work. The exo-MEL pharmacological effects are hereby interpreted in view of changes in the physiological properties and rhythmicity of endogenous melatonin. Finally, we discuss some translational implications for the personalized use of exo-MEL in the clinical practice.

Different levels of circadian (de)synchrony -- where does it hurt?

A network of cellular timers ensures the maintenance of homeostasis by temporal modulation of physiological processes across the day. These so-called circadian clocks are synchronized to geophysical time by external time cues (or zeitgebers). In modern societies, natural environmental cycles are disrupted by artificial lighting, around-the-clock availability of food or shiftwork. Such contradictory zeitgeber input promotes chronodisruption, i.e., the perturbation of internal circadian rhythms, resulting in adverse health outcomes. While this phenomenon is well described, it is still poorly understood at which level of organization perturbed rhythms impact on health and wellbeing. In this review, we discuss different levels of chronodisruption and what is known about their health effects. We summarize the results of disrupted phase coherence between external and internal time vs. misalignment of tissue clocks amongst each other, i.e., internal desynchrony. Last, phase incoherence can also occur at the tissue level itself. Here, alterations in phase coordination can emerge between cellular clocks of the same tissue or between different clock genes within the single cell. A better understanding of the mechanisms of circadian misalignment and its effects on physiology will help to find effective tools to prevent or treat disorders arising from modern-day chronodisruptive environments.

Different levels of circadian (de)synchrony -- where does it hurt?

A network of cellular timers ensures the maintenance of homeostasis by temporal modulation of physiological processes across the day. These so-called circadian clocks are synchronized to geophysical time by external time cues (or zeitgebers). In modern societies, natural environmental cycles are disrupted by artificial lighting, around-the-clock availability of food or shift work. Such contradictory zeitgeber input promotes chronodisruption, i.e., the perturbation of internal circadian rhythms, resulting in adverse health outcomes. While this phenomenon is well described, it is still poorly understood at which level of organization perturbed rhythms impact on health and wellbeing. In this review, we discuss different levels of chronodisruption and what is known about their health effects. We summarize the results of disrupted phase coherence between external and internal time vs. misalignment of tissue clocks amongst each other, i.e., internal desynchrony. Last, phase incoherence can also occur at the tissue level itself. Here, alterations in phase coordination can emerge between cellular clocks of the same tissue or between different clock genes within the single cell. A better understanding of the mechanisms of circadian misalignment and its effects on physiology will help to find effective tools to prevent or treat disorders arising from modern-day chronodisruptive environments.

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.

Drugs Used in Circadian Sleep-Wake Rhythm Disturbances

This article focuses on melatonin and other melatonin receptor agonists and summarizes their circadian phase shifting and sleep-enhancing properties, along with their associated possible safety concerns. The circadian system and circadian rhythm sleep-wake disorders are described, along with the latest American Academy of Sleep Medicine recommendations for the use of exogenous melatonin in treating them. In addition, the practical aspects of using exogenous melatonin obtainable over the counter in the United States, consideration of the effects of concomitant light exposure, and assessing treatment response are discussed.

Non-24-Hour Sleep–Wake Disorder and Tasimelteon: A Review for Practitioners Who Work with Blind People

Introduction

This narrative review summarizes the biology of human circadian rhythms; details the epidemiology, clinical manifestation, and diagnosis of non-24-hour sleep–wake disorder (N24SWD); and reviews the efficacy of possible treatments.

Methods

Searches of targeted phrases, such as “non-24-hour sleep–wake disorder” and “tasimelteon,” were conducted on PubMed between December 2016 and March 2020.

Results

As the world’s population ages, health practitioners frequently work with people who are blind. Damage to the retinal ganglion cells that signal environmental irradiance levels to the suprachiasmatic nucleus prevents many of these individuals from synchronizing their internal clocks to the 24-hour day. As a result, they experience a condition called N24SWD, where the body’s circadian rhythms fall in and out of phase with the solar cycle. The ability to fall asleep and remain asleep is a complex process that depends on many variables, including the release of the neurohormone melatonin. Melatonin is produced at night and is a key regulator of regular sleep cycles. Periods of interrupted sleep, increased sleep latency, and reduced total sleep time occur when melatonin production peaks during daytime. Thus, many persons with N24SWD have difficulty maintaining normal schedules due in part to the mistimed release of melatonin. Randomized clinical trials have shown that melatonin receptor agonist tasimelteon is an effective therapy for individuals with N24SWD. Other treatments have varying efficacy profiles.

Conclusions

Although rare, N24SWD is a serious condition that can impair quality of life for blind persons. Tasimelteon appears to be a safe and efficacious treatment option.

Implications for practitioners

Practitioners can use this information to better understand why blind persons often report difficulties sleeping and to realize that therapeutic options are available to these individuals.

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.

Role of Melatonin in the Management of Sleep and Circadian Disorders in the Context of Psychiatric Illness

PURPOSE OF REVIEW

We present a review of research on the role of melatonin in the management of sleep and circadian disorders, stressing current overall view of the knowledge across psychiatric disorders.

RECENT FINDINGS

Dysregulation of sleep and circadian rhythms has been established in several psychiatric and neurocognitive disorders for long. Recent research confirms this finding consistently across disorders. The secretion of melatonin in schizophrenia and neurocognitive disorders is reduced due to a smaller volume and enlarged calcification of the pineal gland. On the other hand, melatonin dysregulation in bipolar disorder may be more dynamic and caused by light-sensitive melatonin suppression and delayed melatonin secretion. In both cases, exogenous melatonin seems indicated to correct the dysfunction. However, a very limited number of well-designed trials with melatonin to correct sleep and circadian rhythms exist in psychiatric disorders, and the evidence for efficacy is robust only in autism, attention deficit hyperactivity disorder (ADHD), and neurocognitive disorders. This topic has mainly not been of interest for recent work and well-designed trials with objective circadian parameters are few. Overall, recent studies in psychiatric disorders reported that melatonin can be effective in improving sleep parameters such as sleep onset latency, sleep efficiency, and sleep quality. Recent meta-analysis suggests that optimal dosage and dosing time might be important to maximize the efficacy of melatonin. The knowledge base is sufficient to propose well-designed, larger trials with circadian parameters as inclusion and outcome criteria. Based on the partly fragmentary information, we propose testing efficacy in disorders with neurocognitive etiopathology with later and higher dosing, and affective and anxiety disorders with lower and earlier dosing of melatonin. Melatonin is promising for the correction of sleep and circadian abnormalities in psychiatric disorders. However, research results on its effect are still few and need to be accumulated. For effective use of melatonin, it is necessary to consider the appropriate dosage and administration time, depending on the individual abnormality of sleep and circadian rhythms.

Melatonin as an Add-On Treatment of COVID-19 Infection: Current Status

This brief review was written to provide a perspective on the flurry of reports suggesting that melatonin can be an important add-on therapy for COVID-19. Despite the passage of more than 60 years since its discovery and much evidence representing the contrary, there has been great reluctance to conceive melatonin as anything other than a hormone. Many other body chemicals are known to have multiple roles. Melatonin was first shown to be a hormone derived from the pineal gland, to be actively synthesized there only at night, and to act on targets directly or via the G-protein-coupled receptors (GPCRs) superfamily. It is of note that over 40 years ago, it was also established that melatonin is present, synthesized locally, and acts within the gastrointestinal tract. A wider distribution was then found, including the retina and multiple body tissues. In addition, melatonin is now known to have non-hormonal actions, acting as a free radical scavenger, an antioxidant, and as modulating immunity, dampening down innate tissue responses to invaders while boosting the production of antibodies against them. These actions make it a potentially excellent weapon against infection by the SARS-CoV-2 virus. Early published results support that thesis. Recently, a randomized controlled study reported that low doses of melatonin significantly improved symptoms in hospitalized COVID-19 patients, leading to more rapid discharge with no side effects, while significantly decreasing levels of CRP, proinflammatory cytokines, and modulating dysregulated genes governing cellular and humoral immunity. It is now critical that these trials be repeated, with dose-response studies conducted and safety proven. Numerous randomized controlled trials are ongoing, which should complete those objectives while also allowing for a more thorough evaluation of the mechanisms of action and possible applications to other severe diseases.

Circadian Rhythm Sleep-Wake Disorders

PURPOSE OF REVIEW

This article provides an overview of circadian physiology and discusses common presentations and treatment strategies for the circadian rhythm sleep-wake disorders.

RECENT FINDINGS

Circadian rhythms are present throughout the body, and appreciation for the role that circadian dysregulation plays in overall health is increasing, with mounting associations between circadian disruption and cardiometabolic disease risk.

SUMMARY

It is important to recognize the ubiquitous role that circadian rhythms play throughout the brain and body. An understanding of circadian neurophysiology will provide insight into the means by which patients with a variety of neuropathologies at the level of the retina, optic nerve, or hypothalamus may also be at risk for circadian dysfunction.

Workshop report. Circadian rhythm sleep-wake disorders: gaps and opportunities

This White Paper presents the results from a workshop cosponsored by the Sleep Research Society (SRS) and the Society for Research on Biological Rhythms (SRBR) whose goals were to bring together sleep clinicians and sleep and circadian rhythm researchers to identify existing gaps in diagnosis and treatment and areas of high-priority research in circadian rhythm sleep-wake disorders (CRSWD). CRSWD are a distinct class of sleep disorders caused by alterations of the circadian time-keeping system, its entrainment mechanisms, or a misalignment of the endogenous circadian rhythm and the external environment. In these disorders, the timing of the primary sleep episode is either earlier or later than desired, irregular from day-to-day, and/or sleep occurs at the wrong circadian time. While there are incomplete and insufficient prevalence data, CRSWD likely affect at least 800,000 and perhaps as many as 3 million individuals in the United States, and if Shift Work Disorder and Jet Lag are included, then many millions more are impacted. The SRS Advocacy Taskforce has identified CRSWD as a class of sleep disorders for which additional high-quality research could have a significant impact to improve patient care. Participants were selected for their expertise and were assigned to one of three working groups: Phase Disorders, Entrainment Disorders, and Other. Each working group presented a summary of the current state of the science for their specific CRSWD area, followed by discussion from all participants. The outcome of those presentations and discussions are presented here.

The efficacy of combined bright light and melatonin therapies on sleep and circadian outcomes: A systematic review

The aim of this systematic review was to investigate the effects of combined melatonin and bright light therapies on improved sleep and circadian outcomes. We conducted a systematic review that resulted in a total of eight papers meeting criteria. Four papers investigated the effectiveness of combined therapy in inducing a circadian phase shift on healthy participants. Combined therapy outperformed single light and melatonin therapies in phase advancing, but not in delaying, dim light melatonin onset (DLMO). The other four papers investigated the effect of combined therapy on sleep outcomes. Two of them were performed in elderly populations suffering from cognitive decline and two in delayed sleep-wake phase disorder (DSWPD) patients. While combined therapy was more beneficial than single therapy in elderly populations it did not show any benefit in DSWPD patients. The reported adverse effects of melatonin in elderly populations must be carefully considered. Future studies should investigate the separate and combined effect of melatonin and bright light on sleep and circadian outcomes in different target populations.

Divergent Importance of Chronobiological Considerations in High- and Low-dose Melatonin Therapies

Melatonin has been used preclinically and clinically for different purposes. Some applications are related to readjustment of circadian oscillators, others use doses that exceed the saturation of melatonin receptors MT1 and MT2 and are unsuitable for chronobiological purposes. Conditions are outlined for appropriately applying melatonin as a chronobiotic or for protective actions at elevated levels. Circadian readjustments require doses in the lower mg range, according to receptor affinities. However, this needs consideration of the phase response curve, which contains a silent zone, a delay part, a transition point and an advance part. Notably, the dim light melatonin onset (DLMO) is found in the silent zone. In this specific phase, melatonin can induce sleep onset, but does not shift the circadian master clock. Although sleep onset is also under circadian control, sleep and circadian susceptibility are dissociated at this point. Other limits of soporific effects concern dose, duration of action and poor individual responses. The use of high melatonin doses, up to several hundred mg, for purposes of antioxidative and anti-inflammatory protection, especially in sepsis and viral diseases, have to be seen in the context of melatonin's tissue levels, its formation in mitochondria, and detoxification of free radicals.

Circadian Rhythm Sleep-Wake Disorders: a Contemporary Review of Neurobiology, Treatment, and Dysregulation in Neurodegenerative Disease

Circadian rhythms oscillate throughout a 24-h period and impact many physiological processes and aspects of daily life, including feeding behaviors, regulation of the sleep-wake cycle, and metabolic homeostasis. Misalignment between the endogenous biological clock and exogenous light-dark cycle can cause significant distress and dysfunction, and treatment aims for resynchronization with the external clock and environment. This article begins with a brief historical context of progress in the understanding of circadian rhythms, and then provides an overview of circadian neurobiology and the endogenous molecular clock. Various tools used in the diagnosis of circadian rhythm sleep-wake disorders, including sleep diaries and actigraphy monitoring, are then discussed, as are the therapeutic applications of strategically timed light therapy, melatonin, and other behavioral and pharmacological therapies including the melatonin agonist tasimelteon. Management strategies towards each major human circadian sleep-wake rhythm disorder, as outlined in the current International Classification of Sleep Disorders - Third Edition, including jet lag and shift work disorders, delayed and advanced sleep-wake phase rhythm disorders, non-24-h sleep-wake rhythm disorder, and irregular sleep-wake rhythm disorder are summarized. Last, an overview of chronotherapies and the circadian dysregulation of neurodegenerative diseases is reviewed.

Probing the release of the chronobiotic hormone melatonin from hybrid calcium alginate hydrogel beads

A variety of commonly used hydrogels were utilized in the preparation of calcium alginate beads, which incorporate the chronobiotic hormone melatonin (MLT). The in vitro release of the hormone in aqueous media at pH 1.2 and 6.8 was probed in the conjunction with the swelling of the beads and their thermal degradation properties. It has been found that the release of MLT from the beads was reversibly proportional to the extent of their expansion, which depends on the molecular mass/viscosity of the biopolymers present in the beads; the higher the molecular mass/viscosity of the hydrogels the greater the beads swelling and the less the MLT's release. Thermogravimetric analysis (TGA) data support the presence of the components in the hybrid hydrogel beads and elucidate their effects on the thermal stability of the systems. Thus, the physicochemical properties of the biopolymers used, along with their stereoelectronic features modulate the release of MLT from the beads, providing formulations able to treat sleep onset related problems or dysfunctions arising from poor sleep maintenance.

Drugs Used in Circadian Sleep-Wake Rhythm Disturbances

This article focuses on melatonin and other melatonin receptor agonists, and specifically their circadian phase shifting and sleep-enhancing properties. The circadian system and circadian rhythm sleep-wake disorders are briefly reviewed, followed by a summary of the circadian phase shifting, sleep-enhancing properties, and possible safety concerns associated with melatonin and other melatonin receptor agonists. The recommended use of melatonin, including dose and timing, in the latest American Academy of Sleep Medicine Clinical Practice Guidelines for the treatment of intrinsic circadian rhythm disorders is also reviewed. Lastly, the practical aspects of treatment and consideration of clinical treatment outcomes are discussed.

Novel Approaches for Assessing Circadian Rhythmicity in Humans: A Review

The temporal organization of molecular and physiological processes is driven by environmental and behavioral cycles as well as by self-sustained molecular circadian oscillators. Quantification of phase, amplitude, period, and disruption of circadian oscillators is essential for understanding their contribution to sleep-wake disorders, social jet lag, interindividual differences in entrainment, and the development of chrono-therapeutics. Traditionally, assessment of the human circadian system, and the output of the SCN in particular, has required collection of long time series of univariate markers such as melatonin or core body temperature. Data were collected in specialized laboratory protocols designed to control for environmental and behavioral influences on rhythmicity. These protocols are time-consuming, expensive, and not practical for assessing circadian status in patients or in participants in epidemiologic studies. Novel approaches for assessment of circadian parameters of the SCN or peripheral oscillators have been developed. They are based on machine learning or mathematical model-informed analyses of features extracted from 1 or a few samples of high-dimensional data, such as transcriptomes, metabolomes, long-term simultaneous recording of activity, light exposure, skin temperature, and heart rate or in vitro approaches. Here, we review whether these approaches successfully quantify parameters of central and peripheral circadian oscillators as indexed by gold standard markers. Although several approaches perform well under entrained conditions when sleep occurs at night, the methods either perform worse in other conditions such as shift work or they have not been assessed under any conditions other than entrainment and thus we do not yet know how robust they are. Novel approaches for the assessment of circadian parameters hold promise for circadian medicine, chrono-therapeutics, and chrono-epidemiology. There remains a need to validate these approaches against gold standard markers, in individuals of all sexes and ages, in patient populations, and, in particular, under conditions in which behavioral cycles are displaced.

Melatonin for the prevention of postoperative delirium in older adults: a systematic review and meta-analysis

Background

Older surgical patients are at high risk of developing postoperative delirium. Non-pharmacological strategies are recommended for delirium prevention, but no pharmacological agents have compelling evidence to decrease the incidence of delirium. The purpose of this study was to assess whether perioperative melatonin decreases the incidence of delirium in older adults undergoing surgical procedures.

Methods

A systematic search using PubMed/Medline, Embase, PsycINFO, CINAHL, and references of identified articles published in English between January 1990 and October 2017 was performed. Two independent reviewers screened titles and abstracts, and then extracted data following a full-text review of included articles with consensus generation and bias assessment. Studies reporting outcomes for melatonin or ramelteon use to prevent delirium in postoperative hospitalized patients (mean age ≥ 50 years) were eligible for inclusion. Data were pooled using a fixed-effects model to generate a forest plot and obtain a summary odds ratio for the outcome of interest (delirium incidence). Cochran’s Q and I² values were used to investigate heterogeneity.

Results

Of 335 records screened, 6 studies were selected for the qualitative analysis and 6 were included in the meta-analysis (n = 1155). The mean age of patients in included studies ranged from 59 to 84 years. Patients in intervention groups typically received melatonin or ramelteon at daily doses of two to eight milligrams around cardiothoracic, orthopedic, or hepatic surgeries for one to nine days, starting on the evening before or the day of surgery. The incidence of delirium ranged from 0 to 30% in the intervention groups versus 4–33% in the comparator groups, and was significantly reduced in the melatonin group, with a summary effect of the meta-analysis yielding an odds ratio of 0.63 (95% CI 0.46 to 0.87; 0.006; I² = 72.1%). A one study removed analysis reduced overall odds ratio to 0.310 (95% CI 0.19 to 0.50), while reducing heterogeneity (Cochran’s Q = 0.798, I² = 0.000).

Conclusion

Perioperative melatonin reduced the incidence of delirium in older adults in the included studies. While optimal dosing remains an unanswered question, the potential benefit of melatonin and melatonin receptor agonists may make them a reasonable option to use for delirium prevention in older adults undergoing surgical procedures.

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

PURPOSE OF REVIEW

To explore the evidence for using exogenous melatonin in the treatment of sleep disorders, both primary and secondary, in children and adults.

RECENT FINDINGS

A number of recently published meta-analyses have shown that there is evidence for the efficacy of exogenously administered melatonin in a number of sleep disorders. However, melatonin is likely to be prescribed largely for reasons of perceived minimal side-effect profile and very low cost in situations in which high-quality evidence for its usefulness is not forthcoming.

SUMMARY

There is evidence for the efficacy of melatonin in the management of insomnia and some intrinsic disorders of circadian rhythm in adults and children as well as in reducing sleep onset latency in jet-lag and shift work disorder in adults. Melatonin is used routinely in the treatment of rapid-eye movement sleep-behaviour disorder despite limited trial evidence. Increasingly, dual melatonin receptor agonists are being trialled in a variety of sleep disorders. Long-term adverse effects are currently not fully identified.

Approaches to the Pharmacological Management of Jet Lag

For many years now a treatment mitigating the debilitating effects of jet lag has been sought. Rapid travel across time zones leads, in most people, to temporary symptoms, in particular poor sleep, daytime alertness and poor performance. Mis-timed circadian rhythms are considered to be the main factor underlying jet-lag symptoms, together with the sleep deprivation from long haul flights. Virtually all aspects of physiology are rhythmic, from cells to systems, and circadian rhythms are coordinated by a central pacemaker or clock in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN adapts slowly to changes in time zone, and peripheral clocks or oscillators adapt at different rates, such that the organism is in a state of desynchrony from the external environment and internally. Light exposure is the main factor controlling the circadian system and needs to be considered together with any pharmacological interventions. This review covers the relatively new chronobiotic drugs, which can hasten adaptation of the circadian system, together with drugs directly affecting alertness and sleep propensity. No current treatment can instantly shift circadian phase to a new time zone; however, adaptation can be hastened. The melatoninergic drugs are promising but larger trials in real-life situations are needed. For short stopovers it is recommended to preserve sleep and alertness without necessarily modifying the circadian system. New research suggests that modification of clock function via genetic manipulation may one day have clinical applications.

Sleep-Wake Disturbance Related to Ocular Disease: A Systematic Review of Phase-Shifting Pharmaceutical Therapies

Purpose

Light input, via the eyes, is essential for regulating circadian rhythms. Eye diseases can cause disruption of vital biological rhythms. Of totally blind people, 87% report sleep problems. There are no UK guidelines for visual disturbance–related circadian rhythm disruption. Our objective was to systematically review the literature to determine the effectiveness of pharmacological agents on the sleep quality of patients with sleep disturbance related to ocular disease.

Methods

We searched CENTRAL, MEDLINE, EMBASE, PsycINFO, and CINAHL alongside protocol registries and citation searches. We assessed the risk of bias using the Cochrane Risk of Bias Assessment Tool and assessed the strength of overall evidence using GRADE criteria.

Results

Four studies (n=116) met the inclusion criteria. Low-quality evidence showed that melatonin can cause entrainment (1 study), increases in total sleep time (all 3 studies), and reduction in sleep latency (1 study). Low-to-moderate quality evidence showed tasimelteon causes a significant improvement in entrainment, midpoint of sleep timing, lower-quartile of night-time sleep, and upper-quartile of daytime sleep.

Conclusions

Results should be treated with caution as the melatonin studies had risks of bias due to inadequate reporting of randomization and masking procedures. The tasimelteon trial had a risk of reporting bias due to changing the outcomes after enrolling participants. Despite the paucity of trials, melatonin and tasimelteon may cause entrainment and improve subjective sleep measures with limited side effects.

Translational Relevance

Given the relative cost melatonin may be a viable choice for treatment of circadian rhythm sleep disorders in the blind and warrants further research.

Melatonin use in an inpatient academic medical center: Factors affecting provider documentation of patients' sleep quality

OBJECTIVES

Melatonin is commonly prescribed for insomnia despite the 2017 American Academy of Sleep Medicine recommendation against its use due to lack of evidence for efficacy and information on adverse effects. The objectives of this study were to determine what percentage of prescribers document the impact of melatonin on sleep quality in hospitalized patients and to examine factors influencing provider documentation.

METHODS

In this single-center retrospective study, electronic medical records of 200 adults with orders for melatonin over a 6-month period were reviewed. The primary outcome was to evaluate provider documentation of sleep and the impact of melatonin on patients' reported sleep quality. Secondary outcomes included an evaluation of provider medication reconciliation (admission/discharge) and concomitant insomnia therapy. Descriptive and inferential statistics were performed (V13.1 Systat Software, Inc.). P values < 0.05 denoted significance.

RESULTS

Providers documented overall sleep quality for 65 (32.5%) patients (15.47 ± 29.23, range 5 to 100%). Specific mention of melatonin's impact on sleep quality was available for 16 (8%) patients. Fifty-four (27%) patients received melatonin prior to admission, and 73 (36.5%) continued therapy at discharge. For patients discharged on melatonin, the percentage of provider documentation related to patients' sleep quality was higher compared to those discharged without melatonin (41.1% vs. 27.6%; P < 0.049). Fifty-nine (29.5%) patients had concomitant insomnia medications. Provider documentation was greater for patients receiving combination therapy (44.1%) compared to melatonin monotherapy (27.7%; P < 0.024).

CONCLUSION

Documentation of patients' reported sleep quality was lacking for 67.5% of patients. Prescriberswere more likely to document impressions of patients' sleep quality when the patients received melatonin in combination with at least 1 other medication for insomnia. Melatonin was continued upon discharge for an additional 9.5% of study patients who had not been taking melatonin prior to admission. This study demonstrated that melatonin is widely used but narrowly monitored.

Non-24-hour Sleep-Wake Rhythm Disorder

Non-24-hour sleep-wake rhythm disorder is a circadian rhythm sleep-wake disorder characterized by an inability to entrain to the 24-hour environment. Patients present with complaints of insomnia or hypersomnia, with progressive daily shifts of sleep-wake activity on actigraphy or sleep logs. Although first recognized in blind individuals without light perception, it also can be seen in individuals with intact vision. Treatment focuses on timed melatonin in blind individuals, whereas it is more complex in sighted individuals, using multiple time cues, such as light, melatonin, social interactions, feeding, and activity.

Fluorine substituted methoxyphenylalkyl amides as potent melatonin receptor agonists

A series of fluorine substituted methoxyphenylalkyl amides were prepared with different orientations of the fluorine and methoxy groups with respect to the alkylamide side chain and with alkyl sides of differing lengths (n = 1-3). β-Dimethyl and α-methyl derivatives were also synthesised. The compounds were tested as melatonin agonists and antagonists using the pigment aggregation of Xenopus melanophores as the biological assay. A number of these compounds were potent melatonin agonists, the potency depending on the length of the alkyl chain, the orientation of the methoxy and fluorine substituents, the amide chain length and, for the ethyl side-chain analogues, the presence of β-substituents.

Drugs Used in Circadian Sleep-Wake Rhythm Disturbances

This article focuses on melatonin and other melatonin receptor agonists, and specifically their circadian phase shifting and sleep-enhancing properties. The circadian system and circadian rhythm sleep-wake disorders are briefly reviewed, followed by a summary of the circadian phase shifting, sleep-enhancing properties, and possible safety concerns associated with melatonin and other melatonin receptor agonists. The recommended use of melatonin, including dose and timing, in the latest American Academy of Sleep Medicine Clinical Practice Guidelines for the treatment of intrinsic circadian rhythm disorders is also reviewed. Lastly, the practical aspects of treatment and consideration of clinical treatment outcomes are discussed.

Diagnostic and Treatment Challenges of Sighted Non-24-Hour Sleep-Wake Disorder

STUDY OBJECTIVES

To report the diagnostic and treatment challenges of sighted non-24-hour sleep-wake disorder (N24SWD).

METHODS

We report a series of seven sighted patients with N24SWD clinically evaluated by history and sleep diaries, and when available wrist actigraphy and salivary melatonin levels, and treated with timed melatonin and bright light therapy.

RESULTS

Most patients had a history of a delayed sleep-wake pattern prior to developing N24SWD. The typical sleep-wake pattern of N24SWD was seen in the sleep diaries (and in actigraphy when available) in all patients with a daily delay in midpoint of sleep ranging 0.8 to 1.8 hours. Salivary dim light melatonin onset (DLMO) was evaluated in four patients but was missed in one. The estimated phase angle from DLMO to sleep onset ranged from 5.25 to 9 hours. All six patients who attempted timed melatonin and bright light therapy were able to entrain their sleep-wake schedules. Entrainment occurred at a late circadian phase, possibly related to the late timing of melatonin administration, though the patients often preferred late sleep times. Most did not continue treatment and continued to have a non-24-hour sleep-wake pattern.

CONCLUSIONS

N24SWD is a chronic debilitating disorder that is often overlooked in sighted people and can be challenging to diagnose and treat. Tools to assess circadian pattern and timing can be effectively applied to aid the diagnosis. The progressive delay of the circadian rhythm poses a challenge for determining the most effective timing for melatonin and bright light therapies. Furthermore, once the circadian sleep-wake rhythm is entrained, long-term effectiveness is limited because of the behavioral and environmental structure that is required to maintain stable entrainment.

Efficacy of melatonin for sleep disturbance following traumatic brain injury: a randomised controlled trial

BACKGROUND

The study aimed to determine the efficacy of melatonin supplementation for sleep disturbances in patients with traumatic brain injury (TBI).

METHODS

This is a randomised double-blind placebo-controlled two-period two-treatment (melatonin and placebo) crossover study. Outpatients were recruited from Epworth and Austin Hospitals Melbourne, Australia. They had mild to severe TBI (n = 33) reporting sleep disturbances post-injury (mean age 37 years, standard deviation 11 years; 67% men). They were given prolonged-release melatonin formulation (2 mg; Circadin®) and placebo capsules for 4 weeks each in a counterbalanced fashion separated by a 48-hour washout period. Treatment was taken nightly 2 hours before bedtime. Serious adverse events and side-effects were monitored.

RESULTS

Melatonin supplementation significantly reduced global Pittsburgh Sleep Quality Index scores relative to placebo, indicating improved sleep quality [melatonin 7.68 vs. placebo 9.47, original score units; difference -1.79; 95% confidence interval (CI), -2.70 to -0.88; p ≤ 0.0001]. Melatonin had no effect on sleep onset latency (melatonin 1.37 vs. placebo 1.42, log units; difference -0.05; 95% CI, -0.14 to 0.03; p = 0.23). With respect to the secondary outcomes, melatonin supplementation increased sleep efficiency on actigraphy, and vitality and mental health on the SF-36 v1 questionnaire (p ≤ 0.05 for each). Melatonin decreased anxiety on the Hospital Anxiety Depression Scale and fatigue on the Fatigue Severity Scale (p ≤ 0.05 for both), but had no significant effect on daytime sleepiness on the Epworth Sleepiness Scale (p = 0.15). No serious adverse events were reported.

CONCLUSIONS

Melatonin supplementation over a 4-week period is effective and safe in improving subjective sleep quality as well as some aspects of objective sleep quality in patients with TBI.

TRIAL REGISTRATION

Identifier: 12611000734965; Prospectively registered on 13 July 2011.

Depressive disorders: Processes leading to neurogeneration and potential novel treatments

Mood disorders are wide spread with estimates that one in seven of the population are affected at some time in their life (Kessler et al., 2012). Many of those affected with severe depressive disorders have cognitive deficits which may progress to frank neurodegeneration. There are several peripheral markers shown by patients who have cognitive deficits that could represent causative factors and could potentially serve as guides to the prevention or even treatment of neurodegeneration. Circadian rhythm misalignment, immune dysfunction and oxidative stress are key pathologic processes implicated in neurodegeneration and cognitive dysfunction in depressive disorders. Novel treatments targeting these pathways may therefore potentially improve patient outcomes whereby the primary mechanism of action is outside of the monoaminergic system. Moreover, targeting immune dysfunction, oxidative stress and circadian rhythm misalignment (rather than primarily the monoaminergic system) may hold promise for truly disease modifying treatments that may prevent neurodegeneration rather than simply alleviating symptoms with no curative intent. Further research is required to more comprehensively understand the contributions of these pathways to the pathophysiology of depressive disorders to allow for disease modifying treatments to be discovered.

Non-24-Hour Sleep-Wake Rhythm Disorder in the Totally Blind: Diagnosis and Management

Several aspects of human physiology and behavior are dominated by 24-h circadian rhythms with key impacts on health and well-being. These include mainly the sleep–wake cycle, vigilance and performance patterns, and some hormone secretions. The rhythms are generated spontaneously by an internal “pacemaker,” the suprachiasmatic nuclei within the anterior hypothalamus. This master clock has, for most humans, an intrinsic rhythm slightly longer than 24 h. Daily retinal light exposure is necessary for the synchronization of the circadian rhythms with the external 24-h solar environment. This daily synchronization process generally poses no problems for sighted individuals except in the context of jetlag or working night shifts being conditions of circadian desynchrony. However, many blind subjects with no light perception had periodical circadian desynchrony, in the absence of light information to the master clock leading to poor circadian rhythm synchronization. Affected patients experience cyclical or periodic episodes of poor sleep and daytime dysfunction, severely interfering with social, academic, and professional life. The diagnosis of Non-24 Sleep–Wake Rhythm Disorder, also named free-running disorder, non-entrained disorder, or hypernycthemeral syndrome, remains challenging from a clinical point of view due to the cyclical symptoms and should be confirmed by measurements of circadian biomarkers such as urinary melatonin to demonstrate a circadian period outside the normal range. Management includes behavioral modification and melatonin. Tasimelteon, a novel melatonin receptor 1 and 2 agonist, has demonstrated its effectiveness and safety with an evening dose of 20 mg and is currently the only treatment approved by the FDA and the European Medicines Agency.

Efficacy and safety of sublingual ramelteon as an adjunctive therapy in the maintenance treatment of bipolar I disorder in adults: A phase 3, randomized controlled trial

BACKGROUND

The optimal long-term management strategy for bipolar I disorder patients is not yet established. Evidence supports the rationale for circadian rhythm regulation to prevent mood episode relapse in bipolar patients. This study evaluated the efficacy and safety of a new sublingual formulation of the melatonin receptor agonist ramelteon (ramelteon SL) as adjunctive therapy in the maintenance treatment of bipolar I patients.

METHODS

In a double-blinded trial in the United States and Latin America, adult bipolar I disorder patients stable for ≥ 8 weeks before baseline and with a mood episode 8 weeks to 9 months before screening, were randomized to once-daily ramelteon SL 0.1mg (n = 164), 0.4mg (n = 160), or 0.8mg (n = 154), or placebo (n = 164), in addition to their existing treatment. The primary endpoint was time from randomization to relapse of symptoms. The prespecified futility criterion in a planned, unblinded, independent interim analysis was the failure of all ramelteon SL doses to achieve a conditional power ≥ 30% compared with placebo.

RESULTS

No significant differences between any dose of ramelteon SL and placebo were observed. The study was terminated after meeting the futility criteria. Ramelteon SL was well tolerated, with a safety profile consistent with that for oral ramelteon.

LIMITATIONS

A low rate of relapse events precluded detection of any statistically significant difference between groups.

CONCLUSIONS

The study failed to demonstrate the efficacy of ramelteon SL as adjunctive maintenance therapy for bipolar disorder. Interim analyses for futility in clinical studies are valuable in preventing unnecessary exposure of subjects to interventions.

Evidence for the efficacy of melatonin in the treatment of primary adult sleep disorders

Melatonin is a physiological hormone involved in sleep timing and is currently used exogenously in the treatment of primary and secondary sleep disorders with empirical evidence of efficacy, but very little evidence from randomised, controlled studies. The aim of this meta-analysis was to assess the evidence base for the therapeutic effects of exogenous melatonin in treating primary sleep disorders. An electronic literature review search of MEDLINE (1950-present) Embase (1980- present), PsycINFO (1987- present), and Scopus (1990- present), along with a hand-searching of key journals was performed in July 2013 and then again in May 2015. This identified all studies that compared the effect of exogenous melatonin and placebo in patients with primary insomnia, delayed sleep phase syndrome, non 24-h sleep wake syndrome in people who are blind, and rapid eye movement-behaviour disorder. Meta-analyses were performed to determine the magnitude of effect in studies of melatonin in improving sleep. A total of 5030 studies were identified; of these citations, 12 were included for review based on the inclusion criteria of being: double or single-blind, randomised and controlled. Results from the meta-analyses showed the most convincing evidence for exogenous melatonin use was in reducing sleep onset latency in primary insomnia (p = 0.002), delayed sleep phase syndrome (p < 0.0001), and regulating the sleep-wake patterns in blind patients compared with placebo. These findings highlight the potential importance of melatonin in treating certain first degree sleep disorders. The development of large-scale, randomised, controlled trials is recommended to provide further evidence for therapeutic use of melatonin in a variety of sleep difficulties.

Nonphotic Entrainment in Humans?

Although light is accepted as the dominant zeitgeber for entrainment of the human circadian system, there is evidence that nonphotic stimuli may play a role. This review critically assesses the current evidence in support of nonphotic entrainment in humans. Studies involving manipulations of sleep-wake schedules, exercise, mealtimes, and social stimuli are re-examined, bearing in mind the fact that the human circadian clock is sensitive to very dim light and has a free-running period very close to 24 h. Because of light confounds, the study of totally blind subjects with free-running circadian rhythms represents the ideal model to investigate the effects of nonphotic stimuli on circadian phase and period. Strong support for nonphotic entrainment in humans has already come from the study of a few blind subjects with entrained circadian rhythms. However, in these studies the nonphotic stimulus(i) responsible was not identified. The effect of appropriately timed exercise or exogenous melatonin represents the best proof to date of an effect of nonphotic stimuli on human circadian timing. Phase-response curves for both exercise and melatonin have been constructed. Given the powerful effect of feeding as a circadian zeitgeber in various nonhuman species, studies of meal timing are recommended. In conclusion, the available evidence indicates that it remains worthwhile to continue to study nonphotic effects on human circadian timing to identify treatment strategies for shift workers and transmeridian travelers as well as for the blind and possibly the elderly.

A Pre-Screening Questionnaire to Predict Non-24-Hour Sleep-Wake Rhythm Disorder (N24HSWD) among the Blind

STUDY OBJECTIVES

There is currently no questionnaire-based pre-screening tool available to detect non-24-hour sleep-wake rhythm disorder (N24HSWD) among blind patients. Our goal was to develop such a tool, derived from gold standard, objective hormonal measures of circadian entrainment status, for the detection of N24HSWD among those with visual impairment.

METHODS

We evaluated the contribution of 40 variables in their ability to predict N24HSWD among 127 blind women, classified using urinary 6-sulfatoxymelatonin period, an objective marker of circadian entrainment status in this population. We subjected the 40 candidate predictors to 1,000 bootstrapped iterations of a logistic regression forward selection model to predict N24HSWD, with model inclusion set at the p < 0.05 level. We removed any predictors that were not selected at least 1% of the time in the 1,000 bootstrapped models and applied a second round of 1,000 bootstrapped logistic regression forward selection models to the remaining 23 candidate predictors. We included all questions that were selected at least 10% of the time in the final model. We subjected the selected predictors to a final logistic regression model to predict N24SWD over 1,000 bootstrapped models to calculate the concordance statistic and adjusted optimism of the final model. We used this information to generate a predictive model and determined the sensitivity and specificity of the model. Finally, we applied the model to a cohort of 1,262 blind women who completed the survey, but did not collect urine samples.

RESULTS

The final model consisted of eight questions. The concordance statistic, adjusted for bootstrapping, was 0.85. The positive predictive value was 88%, the negative predictive value was 79%. Applying this model to our larger dataset of women, we found that 61% of those without light perception, and 27% with some degree of light perception, would be referred for further screening for N24HSWD.

CONCLUSIONS

Our model has predictive utility sufficient to serve as a pre-screening questionnaire for N24HSWD among the blind.

Tasimelteon: A Review in Non-24-Hour Sleep-Wake Disorder in Totally Blind Individuals

Tasimelteon (Hetlioz(®)) is a dual melatonin receptor agonist indicated for the treatment of Non-24-Hour Sleep-Wake Disorder (Non-24) (free-running disorder). In two randomized, double-masked, multicentre, phase III trials, totally blind individuals with Non-24 who received oral tasimelteon 20 mg once nightly were significantly more likely than those receiving placebo to entrain the circadian pacemaker (the SET trial) and maintain entrainment (the RESET trial). Sleep/wake parameters and functioning were also improved with tasimelteon. Oral tasimelteon was generally well tolerated in totally blind patients with Non-24. In conclusion, tasimelteon is a useful drug for the treatment of Non-24 in totally blind individuals.

Non-24-Hour Sleep-Wake Disorder Revisited - A Case Study

The human sleep-wake cycle is governed by two major factors: a homeostatic hourglass process (process S), which rises linearly during the day, and a circadian process C, which determines the timing of sleep in a ~24-h rhythm in accordance to the external light-dark (LD) cycle. While both individual processes are fairly well characterized, the exact nature of their interaction remains unclear. The circadian rhythm is generated by the suprachiasmatic nucleus ("master clock") of the anterior hypothalamus, through cell-autonomous feedback loops of DNA transcription and translation. While the phase length (tau) of the cycle is relatively stable and genetically determined, the phase of the clock is reset by external stimuli ("zeitgebers"), the most important being the LD cycle. Misalignments of the internal rhythm with the LD cycle can lead to various somatic complaints and to the development of circadian rhythm sleep disorders (CRSD). Non-24-hour sleep-wake disorders (N24HSWD) is a CRSD affecting up to 50% of totally blind patients and characterized by the inability to maintain a stable entrainment of the typically long circadian rhythm (tau > 24.5 h) to the LD cycle. The disease is rare in sighted individuals and the pathophysiology less well understood. Here, we present the case of a 40-year-old sighted male, who developed a misalignment of the internal clock with the external LD cycle following the treatment for Hodgkin's lymphoma (ABVD regimen, four cycles and AVD regimen, four cycles). A thorough clinical assessment, including actigraphy, melatonin profiles and polysomnography led to the diagnosis of non-24-hour sleep-wake disorders (N24HSWD) with a free-running rhythm of tau = 25.27 h. A therapeutic intervention with bright light therapy (30 min, 10,000 lux) in the morning and melatonin administration (0.5-0.75 mg) in the evening failed to entrain the free-running rhythm, although a longer treatment duration and more intense therapy might have been successful. The sudden onset and close timely connection led us to hypothesize that the chemotherapy might have caused a mutation of the molecular clock components leading to the observed elongation of the circadian period.

Sex differences in the circadian profiles of melatonin and cortisol in plasma and urine matrices under constant routine conditions

Conflicting evidence exists as to whether there are differences between males and females in circadian timing. The aim of the current study was to assess whether sex differences are present in the circadian regulation of melatonin and cortisol in plasma and urine matrices during a constant routine protocol. Thirty-two healthy individuals (16 females taking the oral contraceptive pill (OCP)), aged 23.8 ± 3.7 (mean ± SD) years, participated. Blood (hourly) and urine (4-hourly) samples were collected for measurement of plasma melatonin and cortisol, and urinary 6-sulfatoxymelatonin (aMT6s) and cortisol, respectively. Data from 28 individuals (14 females) showed no significant differences in the timing of plasma and urinary circadian phase markers between sexes. Females, however, exhibited significantly greater levels of plasma melatonin and cortisol than males (AUC melatonin: 937 ± 104 (mean ± SEM) vs. 642 ± 47 pg/ml.h; AUC cortisol: 13581 ± 1313 vs. 7340 ± 368 mmol/L.h). Females also exhibited a significantly higher amplitude rhythm in both hormones (melatonin: 43.8 ± 5.8 vs. 29.9 ± 2.3 pg/ml; cortisol: 241.7 ± 23.1 vs. 161.8 ± 15.9 mmol/L). Males excreted significantly more urinary cortisol than females during the CR (519.5 ± 63.8 vs. 349.2 ± 39.3 mol) but aMT6s levels did not differ between sexes. It was not possible to distinguish whether the elevated plasma melatonin and cortisol levels observed in females resulted from innate sex differences or the OCP affecting the synthetic and metabolic pathways of these hormones. The fact that the sex differences observed in total plasma concentrations for melatonin and cortisol were not reproduced in the urinary markers challenges their use as a proxy for plasma levels in circadian research, especially in OCP users.

Tasimelteon for non-24-hour sleep-wake disorder in totally blind people (SET and RESET): two multicentre, randomised, double-masked, placebo-controlled phase 3 trials

BACKGROUND

Most totally blind people have non-24-hour sleep-wake disorder (non-24), a rare circadian rhythm disorder caused by an inability of light to reset their circadian pacemaker. In two consecutive placebo-controlled trials (SET and RESET), we assessed safety and efficacy (in terms of circadian entrainment and maintenance) of once-daily tasimelteon, a novel dual-melatonin receptor agonist.

METHODS

We undertook the placebo-controlled, randomised, double-masked trials in 27 US and six German clinical research centres and sleep centres. We screened totally blind adults (18-75 years of age), who were eligible for the randomisation phase of SET if they had a non-24-hour circadian period (τ) of 24·25 h or longer (95% CI greater than 24·0 and up to 24·9 h), as calculated from measurements of urinary 6-sulphatoxymelatonin rhythms. For SET, we used block randomisation to assign patients (1:1) to receive tasimelteon (20 mg) or placebo every 24 h at a fixed clock time 1 h before target bedtime for 26 weeks. Patients who entered the open-label group receiving tasimelteon in SET or who did not meet the SET inclusion criteria but did meet the RESET inclusion criteria were screened for RESET. A subset of the patients who entered the open-label group before the RESET study and who had eligible τ values were screened for RESET after completing the open-label treatment. In RESET, we withdrew tasimelteon in a randomised manner (1:1) in patients who responded (ie, entrained) after a tasimelteon run-in period. Entrainment was defined as having τ of 24·1 h or less and a 95% CI that included 24·0 h. In SET, the primary endpoint was the proportion of entrained patients, assessed in the intention-to-treat population. The planned step-down primary endpoint assessed the proportion of patients who had a clinical response (entrainment at month 1 or month 7 plus clinical improvement, measured by the Non-24 Clinical Response Scale). In RESET, the primary endpoint was the proportion of non-entrained patients, assessed in the intention-to-treat population. Safety assessments included adverse events and clinical laboratory measures, assessed in all treated patients. These trials are registered with ClinicalTrials.gov, numbers NCT01163032 and NCT01430754.

FINDINGS

Between Aug 25, 2010, and July 5, 2012, we screened 391 totally blind patients for SET, of whom 84 (22%) were assigned to receive tasimelteon (n=42) or placebo (n=42). Two patients in the tasimelteon group and four in the placebo group discontinued the study before τ was measured, due to adverse events, withdrawal of consent, and a protocol deviation. Circadian entrainment occurred in eight (20%) of 40 patients in the tasimelteon group compared with one (3%) of 38 patients in the placebo group at month 1 (difference 17%, 95% CI 3·2-31·6; p=0·0171). Nine (24%) of 38 patients showed a clinical response, compared with none of 34 in the placebo group (difference 24%, 95% CI 8·4-39·0; p=0·0028). Between Sept 15, 2011, and Oct 4, 2012, we screened 58 patients for eligibility in RESET, 48 (83%) of whom had τ assessed and entered the open-label tasimelteon run-in phase. 24 (50%) patients entrained, and 20 (34%) were enrolled in the randomisation phase. Two (20%) of ten patients who were withdrawn to placebo remained entrained compared with nine (90%) of ten who continued to receive tasimelteon (difference 70%, 95% CI 26·4-100·0; p=0·0026). No deaths were reported in either study, and discontinuation rates due to adverse events were comparable between the tasimelteon (3 [6%] of 52 patients) and placebo (2 [4%] of 52 patients) treatment courses. The most common side-effects associated with tasimelteon in SET were headache (7 [17%] of 42 patients given tasimelteon vs 3 [7%] of 42 patients given placebo), elevated liver enzymes (4 [10%] vs 2 [5%]), nightmares or abnormal dreams (4 [10%] vs none), upper respiratory tract infection (3 [7%] vs none], and urinary tract infections (3 [7%] vs 1 [2%]).

INTERPRETATION

Once-daily tasimelteon can entrain totally blind people with non-24; however, continued tasimelteon treatment is necessary to maintain these improvements.

FUNDING

Vanda Pharmaceuticals.

Clinical Practice Guideline for the Treatment of Intrinsic Circadian Rhythm Sleep-Wake Disorders: Advanced Sleep-Wake Phase Disorder (ASWPD), Delayed Sleep-Wake Phase Disorder (DSWPD), Non-24-Hour Sleep-Wake Rhythm Disorder (N24SWD), and Irregular Sleep-Wake Rhythm Disorder (ISWRD). An Update for 2015: An American Academy of Sleep Medicine Clinical Practice Guideline

A systematic literature review and meta-analyses (where appropriate) were performed and the GRADE approach was used to update the previous American Academy of Sleep Medicine Practice Parameters on the treatment of intrinsic circadian rhythm sleep-wake disorders. Available data allowed for positive endorsement (at a second-tier degree of confidence) of strategically timed melatonin (for the treatment of DSWPD, blind adults with N24SWD, and children/ adolescents with ISWRD and comorbid neurological disorders), and light therapy with or without accompanying behavioral interventions (adults with ASWPD, children/adolescents with DSWPD, and elderly with dementia). Recommendations against the use of melatonin and discrete sleep-promoting medications are provided for demented elderly patients, at a second- and first-tier degree of confidence, respectively. No recommendations were provided for remaining treatments/ populations, due to either insufficient or absent data. Areas where further research is needed are discussed.

Caffeine does not entrain the circadian clock but improves daytime alertness in blind patients with non-24-hour rhythms

•

Most totally blind individuals have Non-24-Hour Sleep–Wake Disorder (N24HSWD).

•

Optimal treatment should reset the underlying non-entrained circadian pacemaker.

•

We tested daily caffeine treatment (150 mg, 10 a.m.) in three blind patients with N24HSWD.

•

Caffeine treatment improved daytime alertness at adverse circadian phases.

•

Caffeine treatment was unable to entrain the circadian clock.

Objective/Background

Totally blind individuals are highly likely to suffer from Non-24-Hour Sleep-Wake Disorder due to a failure of light to reset the circadian pacemaker in the suprachiasmatic nuclei. In this outpatient case series, we investigated whether daily caffeine administration could entrain the circadian pacemaker in non-entrained blind patients to alleviate symptoms of non-24-hour sleep–wake disorder.

Patients/Methods

Three totally blind males (63.0 ± 7.5 years old) were studied at home over ~4 months. Urinary 6-sulphatoxymelatonin (aMT6s) rhythms were measured for 48 h every 1–2 weeks. Participants completed daily sleep–wake logs, and rated their alertness and mood using nine-point scales every ~2–4 h while awake on urine sampling days. Caffeine capsules (150 mg per os) were self-administered daily at 10 a.m. for approximately one circadian beat cycle based on each participant's endogenous circadian period τ and compared to placebo (n = 2) or no treatment (n = 1) in a single-masked manner.

Results

Non-24-h aMT6s rhythms were confirmed in all three participants (τ range = 24.32–24.57 h). Daily administration of 150 mg caffeine did not entrain the circadian clock. Caffeine treatment significantly improved daytime alertness at adverse circadian phases (p < 0.0001) but did not decrease the occurrence of daytime naps compared with placebo.

Conclusions

Although caffeine was able to improve daytime alertness acutely and may therefore provide temporary symptomatic relief, the inability of caffeine to correct the underlying circadian disorder means that an entraining agent is required to treat Non-24-Hour Sleep–Wake Disorder in the blind appropriately.

Prolonged release melatonin for improving sleep in totally blind subjects: a pilot placebo-controlled multicenter trial

INTRODUCTION

Melatonin, secreted by the pineal gland during the night phase, is a regulator of the biological clock and sleep tendency. Totally blind subjects frequently report severe, periodic sleep problems, with 50%-75% of cases displaying non-24-hour sleep-wake disorder (N24HSWD) due to inability to synchronize with the environmental day-night cycle. Melatonin immediate-release preparations are reportedly effective in N24HSWD. Here, we studied the efficacy and safety of prolonged-release melatonin (PRM), a registered drug for insomnia, for sleep disorders in totally blind subjects living in normal social environments. The primary endpoint was demonstration of clinically meaningful effects on sleep duration (upper confidence interval [CI] limit >20 minutes whether significant or not) to allow early decision-making on further drug development in this indication.

TRIAL REGISTRATION

ClinicalTrials.gov registry - NCT00972075.

METHODS

In a randomized, double-blind, placebo-controlled proof-of-principle study, 13 totally blind subjects had 2 weeks' placebo run-in, 6 weeks' randomized (1:1) PRM (Circadin(®)) or placebo nightly, and 2 weeks' placebo run-out. Outcome measures included daily voice recorded sleep diary, Clinical Global Impression of Change (CGIC), WHO-Five Well-being Index (WHO-5), and safety.

RESULTS

Mean nightly sleep duration improved by 43 minutes in the PRM and 16 minutes in the placebo group (mean difference: 27 minutes, 95% CI: -14.4 to 69 minutes; P=0.18; effect size: 0.82) meeting the primary endpoint. Mean sleep latency decreased by 29 minutes with PRM over placebo (P=0.13; effect size: 0.92) and nap duration decreased in the PRM but not placebo group. The variability in sleep onset/offset and latency tended to decrease during PRM but not placebo treatment. The potentially beneficial effects of PRM persisted during the 2 weeks of discontinuation period, consistent with clock stabilizing effects. PRM was well-tolerated, adverse events were of mild or moderate severity and similar between PRM and placebo.

CONCLUSION

Nightly use of PRM may potentially improve patient-reported sleep difficulties in totally blind individuals trying to adhere to normal social lifestyle. A larger study powered to demonstrate a statistically significant effect is warranted.

Protecting the melatonin rhythm through circadian healthy light exposure

Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.