Role of the melatonin system in the control of sleep: therapeutic implications

Melatonin stimulates the nonamyloidogenic processing of βAPP through the positive transcriptional regulation of ADAM10 and ADAM17

Melatonin controls many physiological functions including regulation of the circadian rhythm and clearance of free radicals and neuroprotection. Importantly, melatonin levels strongly decrease as we age and patients with Alzheimer's disease (AD) display lower melatonin than age-matched controls. Several studies have reported that melatonin can reduce aggregation and toxicity of amyloid-β peptides that are produced from the β-amyloid precursor protein (βAPP). However, whether melatonin can directly regulate the βAPP-cleaving proteases ('secretases') has not been investigated so far. In this study, we establish that melatonin stimulates the α-secretase cleavage of βAPP in cultured neuronal and non-neuronal cells. This effect is fully reversed by ADAM10- and ADAM17-specific inhibitors and requires both plasma membrane-located melatonin receptor activation, and ERK1/2 phosphorylation. Moreover, we demonstrate that melatonin upregulates both ADAM10 and ADAM17 catalytic activities and endogenous protein levels. Importantly, genetic depletion of one or the other protease in mouse embryonic fibroblasts prevents melatonin stimulating constitutive and PKC-regulated sAPPα secretion and ADAM10/ADAM17 catalytic activities. Furthermore, we show that melatonin induces ADAM10 and ADAM17 promoter transactivation, and we identify the targeted promoter regions. Finally, we correlate melatonin-dependent sAPPα production with a protection against staurosporine-induced apoptosis. Altogether, our results provide the first demonstration that melatonin upregulates the nonamyloidogenic ADAM10 and ADAM17 proteases through melatonin receptor activation, ERK phosphorylation and the transactivation of some specific regions of their promoters and further underline the preventive rather than curative nature of melatonin regarding AD treatment.

Melatonin and melatonin agonist for delirium in the elderly patients

The objective of this review is to summarize the available data on the use of melatonin and melatonin agonist for the prevention and management of delirium in the elderly patients from randomized controlled trials (RCTs). A systematic search of 5 major databases PubMed, MEDLINE, PsychINFO, Embase, and Cochrane Library was conducted. This search yielded a total of 2 RCTs for melatonin. One study compared melatonin to midazolam, clonidine, and control groups for the prevention and management of delirium in individuals who were pre- and posthip post-hip arthroplasty. The other study compared melatonin to placebo for the prevention of delirium in older adults admitted to an inpatient internal medicine service. Data from these 2 studies indicate that melatonin may have some benefit in the prevention and management of delirium in older adults. However, there is no evidence that melatonin reduces the severity of delirium or has any effect on behaviors or functions in these individuals. Melatonin was well tolerated in these 2 studies. The search for a melatonin agonist for delirium in the elderly patients yielded 1 study of ramelteon. In this study, ramelteon was found to be beneficial in preventing delirium in medically ill individuals when compared to placebo. Ramelteon was well tolerated in this study.

Complementary and integrative medicine for older adults in palliative care

Complementary and Integrative Medicine (CIM) encompasses many diverse therapies, including natural products and mind and body practices. Use of CIM is common and can benefit patients in palliative care. However, because patients in palliative care are often frail and elderly, the clinician should consider a patient's comorbidities before recommending certain therapies, such as natural products. In this article, specific examples of CIM are provided for symptoms commonly seen in palliative care.

Melatonin improves sleep in children with epilepsy: a randomized, double-blind, crossover study

OBJECTIVE

Insomnia, especially maintenance insomnia, is widely prevalent in epilepsy. Although melatonin is commonly used, limited data address its efficacy. We performed a randomized, double-blind, placebo-controlled, crossover study to identify the effects of melatonin on sleep and seizure control in children with epilepsy.

METHODS

Eleven prepubertal, developmentally normal children aged 6-11 years with epilepsy were randomized by a software algorithm to receive placebo or a 9-mg sustained release (SR) melatonin formulation for four weeks, followed by a one-week washout and a four-week crossover condition. The pharmacy performed blinding; patients, parents, and study staff other than a statistician were blinded. The primary outcomes were sleep onset latency and wakefulness after sleep onset (WASO) measured on polysomnography. The secondary outcomes included seizure frequency, epileptiform spike density per hour of sleep on electroencephalogram (EEG), and reaction time (RT) measures on psychomotor vigilance task (PVT). Statistical tests appropriate for crossover designs were used for the analysis.

RESULTS

Data were analyzed from 10 subjects who completed the study. Melatonin decreased sleep latency (mean difference, MD, of 11.4 min and p = 0.02) and WASO (MD of 22 min and p = 0.04) as compared to placebo. No worsening of spike density or seizure frequency was seen. Additionally, slow-wave sleep duration and rapid eye movement (REM) latency were increased with melatonin and REM sleep duration was decreased. These changes were statistically significant. Worsening of headache was noted in one subject with migraine on melatonin.

CONCLUSION

SR melatonin resulted in statistically significant decreases in sleep latency and WASO. No clear effects on seizures were observed, but the study was too small to allow any conclusions to be drawn in this regard.

Complementary and alternative medicine treatments for children with autism spectrum disorders

There are many treatments in current use for core and associated symptoms of autism spectrum disorders (ASD). This review discusses the complementary and alternative medical (CAM) treatments commonly added to conventional interventions for children with ASD, including natural products, mind and body practices, and other biomedical treatments. The article focuses on factors associated with use of CAM, the empirical evidence for the most frequently used treatments, and how clinicians work with families who choose CAM treatments. Some treatments have been ineffective, some have unacceptable potential side effects, and others require more study in depth.

The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature

A systematic review was conducted using Samueli Institute’s Rapid Evidence Assessment of the Literature (REAL^©) process to determine the evidence base for melatonin as an agent to optimize sleep or improve sleep quality, and generalize the results to a military, civilian, or other healthy, active, adult population. Multiple databases were searched yielding 35 randomized controlled trials (RCTs) meeting the review’s inclusion criteria, which were assessed for methodological quality as well as for melatonin effectiveness. The majority of included studies were high quality (83.0%). Overall, according to Grading Recommendations, Assessment Development and Evaluation (GRADE) methodology, weak recommendations were made for preventing phase shifts from jet lag, for improving insomnia in both healthy volunteers and individuals with a history of insomnia, and for initiating sleep and/or improving sleep efficacy. Based on the literature to date, no recommendations for use in shift workers or to improve hormonal phase shift changes in healthy people can be made at this time. Larger and longer-duration RCTs utilizing well characterized products are needed to warrant melatonin recommendations in young, healthy adults.

Impairment in circadian activity rhythms occurs during dexamethasone therapy in children with leukemia

BACKGROUND

Circadian rhythm disturbances in adults with cancer are associated with fatigue, time to relapse, and death. This study of circadian activity rhythms (CAR) of children with acute lymphoblastic leukemia (ALL) on continuation chemotherapy aimed to describe CAR before and after starting dexamethasone, and to determine whether fatigue was associated with less robust CAR.

PROCEDURE

This was a secondary analysis of data from a multi-institutional study in which children with ALL aged 5-18 years wore an actigraph for 10 consecutive 24-hour periods, five before and five during dexamethasone therapy. CAR parameters measured by actigraphy were calculated for each 5-day period, including peak activity, MESOR, amplitude, acrophase, and circadian quotient. Fatigue was measured on study days 2, 5, 7, and 10 by parent-report and self-report for children ≥ 7 years.

RESULTS

Eighty-two children qualified for CAR analysis, and 87 for analysis of daily peak activity patterns and fatigue. Mean age was 8.8 ± 3.3 years. Peak activity, MESOR, and amplitude significantly decreased during dexamethasone therapy. Children on high-dose dexamethasone (8 or 12 mg/m(2)/d) had significantly higher (better, or more robust) values of several CAR parameters than those on low-dose (6 mg/m(2)/d). There was a significant trend of decreasing daily pattern of peak activity during dexamethasone therapy only. Fatigue increased across the study and was associated with decreasing CAR peak activity, MESOR, and amplitude.

CONCLUSIONS

Dexamethasone initiation was associated with a decrease in several CAR parameters, and a significant decrease in the trend of daily peak activity. Fatigue was associated with less robust CAR.

Circadian disruption and fatal ovarian cancer

BACKGROUND

The International Agency for Research on Cancer determination that shift work is a "probable" human carcinogen was based primarily on studies of breast cancer but it was also noted that additional aspects of circadian disruption and other cancer sites deserved further research.

PURPOSE

To examine possible associations of three measures of circadian disruption: nontypical work schedules, nightly sleep duration, and monthly frequency of insomnia with risk of fatal ovarian cancer in a sample of American women.

METHODS

Several measures of circadian disruption and other information were assessed in 1982 from 161,004 employed women in the American Cancer Society's Cancer Prevention Study-II, a cohort that has been followed for mortality through 2010. In 2013, Cox proportional hazards regression was used to model the relative risks (RRs) and 95% CIs of death from ovarian cancer for categories of each indicator of circadian disruption.

RESULTS

Over 28 years of follow-up, 1289 deaths from ovarian cancer occurred in the at-risk cohort. Compared to fixed daytime work, a rotating schedule was associated with an elevated risk of fatal ovarian cancer (RR=1.27, 95% CI=1.03, 1.56). No significant associations were observed for sleep duration (p trend=0.24) or insomnia (p trend=0.44).

CONCLUSIONS

In this large prospective study, there was a higher risk of fatal ovarian cancer in women who reported a rotating work schedule. These findings and the high prevalence of rotating shift schedules underscore the need for further research examining the role of work schedule and risk of ovarian cancer.

Media use and sleep among boys with autism spectrum disorder, ADHD, or typical development

OBJECTIVE

The current study examined the relationships between media use (television, computer, and video games) and sleep among boys with autism spectrum disorder (ASD) compared with those with attention-deficit/hyperactivity disorder (ADHD) or with typical development (TD).

METHODS

Participants included parents of boys with ASD (n = 49), ADHD (n = 38), or TD (n = 41) (ages 8-17 years). Questionnaires assessed daily hours of media use, bedroom access to media, and average sleep hours per night.

RESULTS

Bedroom media access was associated with less time spent sleeping per night, irrespective of diagnostic group. Bedroom access to a television or a computer was more strongly associated with reduced sleep among boys with ASD compared with boys with ADHD or TD. Multivariate models showed that, in addition to bedroom access, the amount of time spent playing video games was uniquely associated with less sleep among boys with ASD. In the ASD group only, the relationship between bedroom access to video games and reduced sleep was mediated by hours of video game play.

CONCLUSIONS

The current results suggest that media-related variables may be an important consideration in understanding sleep disturbances in children with ASD. Further research is needed to better characterize the processes by which media use may affect sleep among individuals with ASD. Overall, the current findings suggest that screen-based media time and bedroom media access should be routinely assessed and may be important intervention targets when addressing sleep problems in children with ASD.

The influence of vitamin D supplementation on melatonin status in patients with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) incidence is higher in geographic regions with less sunlight exposure. Both vitamin D and melatonin are essential mediators of the effect of sunlight in health, and as such are candidates to play a key role in MS. We hypothesized that vitamin D and melatonin may have related influences in patients with MS.

METHODS

In a randomized, double blind study of 40 IFN-β treated MS patients, 21 patients were assigned to 800 IU of vitamin D3 per day (low dose), while 19 patients received 4,370 IU vitamin D3 per day (high dose) for one year. Serum 25-hydroxy-vitamin-D (25-OH-D) and nighttime urine melatonin metabolite, 6-sulphatoxy-melatonin (6-SMT), were measured at baseline, 3 months and 1 year from enrolment.

RESULTS

After 3 months supplementation, 25-OH-D levels increased and nighttime melatonin secretion decreased significantly in the high dose group, but not in the low dose group. After 1 year, a decrease in 25-OH-D levels, accompanied by an increase of urine nighttime 6-SMT were observed in the high dose group. Percent change in serum 25-OH-D was significantly and negatively correlated with percent change in urine 6-SMT after 3 months and between 3 months to 1 year. 25-OH-D levels by the end of the study were significantly and negatively correlated to BMI.

CONCLUSIONS

Melatonin secretion is negatively correlated with alterations in serum 25-OH-D in IFN-β treated patients with MS. The finding suggests that melatonin should be considered as a potential mediator of vitamin D neuro-immunomodulatory effects in patients with MS.

Maternal stress induces adult reduced REM sleep and melatonin level

We have previously reported that neonatal maternal deprivation (MD) resulted in a decrease of total sleep and an increase of orexin A in adult rats. Now, we characterized features of sleep, activity, and melatonin levels in rats neonatally treated with MD and control (MC) procedures. Adult male Sprague-Dawley rats were treated with either MD or MC procedures for 10 days starting at postnatal day 4. At 3 months of age, sleep was recorded for 48 h in one set of MD and MC rats, while another set of MD and MC rats was measured for locomotor activity (under LD = 12:12). Melatonin levels in the blood, pineal gland, and hypothalamus were measured as well as clock protein level in the hypothalamus. Compared to the MC rats, REM sleep in the MD rats was significantly reduced in the light periods but not in the dark periods. Both quiet wake and total wake in the MD rats were significantly increased during the light period compared to the MC rats. The weight of the pineal gland of the MD rats was significantly smaller than in MC rats. Melatonin levels of the MD group were significantly reduced in the pineal gland and hypothalamus compared to the MC group. No significant difference was identified between groups in the expression of the clock protein in the hypothalamus. Neonatal MD resulted in reduced REM sleep and melatonin levels, without changes of circadian cycle of locomotor activity and levels of clock protein.

Methylphenidate effects on blood serotonin and melatonin levels may help to synchronise biological rhythms in children with ADHD

The neuroendocrine mediators that may contribute to ADHD (Attention deficit and hyperactivity disorder), serotonin and melatonin, are both thought to regulate circadian rhythms, neurological function and stress response. The objective of this study was to determine the effect of the chronic administration of prolonged release methylphenidate (PRMPH) on daily variations in blood serotonin and melatonin and on the excretion of 6-sulphatoxy-melatonin. A total of 179 children (136 males, 42 females) between the ages of 5 and 14 (9.70 ± 2.55) years were enrolled in a controlled quasi-experimental open clinical study. Of the sample, there were 136 Children with ADHD (based on DSM-IV-TR criteria), who were further grouped into subtypes, and the 42 siblings of the participants who did not ADHD patients. Blood samples were taken at 20:00 and 09:00; urine was collected between 21:00 and 09:00. In the ADHD group, the study protocol was repeated after 4.61 ± 2.3 months of treatment. Measurements included melatonin and serotonin by RIA and urine 6-S-aMT by ELISA. Factorial analyses were conducted by STATA 12.0.

RESULTS

ADHD patients showed reduced morning serotonin with a daily profile that was different than the control group due to the predominance of nocturnal concentrations. PRMPH did not result in any significant changes. Melatonin and its daily profile did not differ between controls and the ADHD group with a diurnal rhythm showing higher morning levels that disappear after PRMPH administration. Melatonin was higher in children with predominantly hyperactive-impulsive/conduct disorder subtype. PRMPH resulted in a decrease in 6-S-aMT excretion for both ADHD subtypes.

CONCLUSION

Chronic treatment with prolonged release methylphenidate induces subtle changes in the daily fluctuations and concentrations of both serotonin and melatonin. Improvement in Children's Depression Inventory (CDI) scores was not related to a morning increase in serotonin.

Neurophysiology of circadian rhythm sleep disorders of children with neurodevelopmental disabilities

This article reviews circadian rhythm sleep disorders (CRSDs) of children with neurodevelopmental disabilities. These sleep disturbances frequently occur in this population but they are misunderstood and under diagnosed. The causes and features of CRSD in children with brain disorders differ in many ways from those seen in typically developing children. It is the brain, including the eyes, which regulates sleep and circadian rhythmicity by modulating pineal melatonin production/secretion and when there is significant brain damage, the sleep/wake patterns may be modified. In most instances CRSD are not disorders of the suprachiasmatic nuclei because these small hypothalamic structures only adjust their functions to the changing photic and non-photic modulatory influences. Each form of CRSD is accompanied by characteristic changes in serum melatonin levels and clinical features. When nocturnal melatonin production/secretion is inappropriately timed or impaired in relation to the environment, timed melatonin replacement therapy will often be beneficial. In this review an attempt is made to clarify the neurophysiological mechanisms underlying the various forms of CRSD because without understanding the photic and non-photic influences on sleep, these sleep disorders can not be fully characterized, defined or even appropriately treated. In the future, the existing definitions for the different forms of CRSD should be modified by experts in pediatric sleep medicine in order to include children with neurodevelopmental disabilities.

Sleep disturbance after pinealectomy in patients with pineocytoma WHO°I

BACKGROUND

Because the pineal gland produces melatonin, it is suggested to be involved in the regulation of sleep and circadian rhythm, though there is scant proof of this. Tumors of the pineal gland are rare and various in terms of histological and biological malignancy. We evaluated the occurrence of subjective sleep disturbances in nine patients who underwent a pinealectomy due to pineocytoma WHO°I without additional therapy.

METHODS

Patients with intracranial low-grade lesions and patients without a craniotomy who underwent a microscopic lumbar discectomy were matched to our study group by gender, age, and date of surgery. We used standardized sleep questionnaires on sleepiness during the daytime, sleep disturbances, and general pathologic sleep patterns.

RESULTS

Patients who underwent a craniotomy either without a pinealectomy (7.2 ± 2.0 points) or with a pinealectomy experienced increased sleep disturbances (6.6 ± 1.3 points) compared to patients who had a lumbar discectomy (2.8 ± 0.4 points), according to the Pittsburgh Sleep Quality Index (PSQI) (p < 0.05). Moreover, sleep disturbances as measured by the insomnia severity index (ISI) were most pronounced in patients who underwent a craniotomy without a pinealectomy (10.4 ± 3.1 points) compared to patients who underwent a pinealectomy or discectomy (5.9 ± 1.9 and 3.3 ± 1.3 points).

CONCLUSIONS

Pinealectomy itself did not cause specific sleep impairment, but craniotomy in general did. This interesting and clinically relevant finding needs further investigation.

New quinoxaline derivatives as potential MT₁ and MT₂ receptor ligands

Ever since the idea arose that melatonin might promote sleep and resynchronize circadian rhythms, many research groups have centered their efforts on obtaining new melatonin receptor ligands whose pharmacophores include an aliphatic chain of variable length united to an N-alkylamide and a methoxy group (or a bioisostere), linked to a central ring. Substitution of the indole ring found in melatonin with a naphthalene or quinoline ring leads to compounds of similar affinity. The next step in this structural approximation is to introduce a quinoxaline ring (a bioisostere of the quinoline and naphthalene rings) as the central nucleus of future melatoninergic ligands.

The effects of shift work on physical and mental health

Occupational engagement is a pre-requisite for continuous income opportunities. Among the changing social circumstances work-related conditions play an increasingly eminent role in psychological and mental well-being. The public discusses the question of a possible association between the demands of modern work life and the increases of psychological, psychosomatic and cardiovascular disorders. Given the socioeconomic implications of psychiatric and psychosomatic suffering in the general population, there is a need to further elucidate the causes of their increasing incidence. From a medical point of view, any organization of work disrupting the phased circadian rhythms for bio-psycho-social processes and functioning of the individual are interesting against the background of clock genes and certain biological functions that are organized in a circadian fashion. The authors review the influence of shift work as a form of systematic desynchronization of inner clock systems on the endocrine, the physical, and the mental level. The significance of the findings in the field is discussed along with future directions of conclusive research.

Circadian regulation of pineal gland rhythmicity

The pineal gland is a neuroendocrine organ of the brain. Its main task is to synthesize and secrete melatonin, a nocturnal hormone with diverse physiological functions. This review will focus on the central and pineal mechanisms in generation of mammalian pineal rhythmicity including melatonin production. In particular, this review covers the following topics: (1) local control of serotonin and melatonin rhythms; (2) neurotransmitters involved in central control of melatonin; (3) plasticity of the neural circuit controlling melatonin production; (4) role of clock genes in melatonin formation; (5) phase control of pineal rhythmicity; (6) impact of light at night on pineal rhythms; and (7) physiological function of the pineal rhythmicity.

Melatonin for non-respiratory sleep disorders in visually impaired children

BACKGROUND

Exogenous melatonin helps in regulating the circadian rhythm and is widely used for the management of sleep disorders in visually impaired children.

OBJECTIVES

The aim of the review was to assess melatonin therapy for treatment of non-respiratory sleep disorders in visually impaired children, with regard to improvement in sleep habit, sleep scheduling and sleep maintenance, when compared with placebo or no treatment.

SEARCH METHODS

We searched the following databases between February 2011 and July 2011: the Cochrane Central Register of Controlled Trials (CENTRAL) 2011(1) searched on 4th February 2011; MEDLINE (1950 to June Week 3, 2011) searched on 20th June 2011; EMBASE (1980 to June Week 4, 2011) searched on 7th July 2011; CINAHL (1937 to 21 September 2011); the metaRegister of Controlled Trials (this includes ClinicalTrial.gov) searched 20 July 2011, and reference lists of papers identified after initial screening.

SELECTION CRITERIA

We planned to include randomized controlled trials (RCTs) and quasi-RCTs, including cross-over studies. Treatment would be exogenous melatonin. Control groups could be placebo, other medication for sleep disorders or no treatment. Outcomes sought were improved sleep with regard to timing and duration, quality of life and adverse events.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trials for inclusion in the review.

MAIN RESULTS

We did not find any studies fulfilling the inclusion criteria, therefore no outcome data are reported.We identified nine studies after initial screening and, after further evaluation, we excluded these. The excluded studies involved a total of 163 individuals aged two years to 18 years. We excluded studies for three main reasons: they were non-randomized or case series studies, they were studies of people over 18 years of age or even where the study was randomised, the study population was mixed and results pertaining to the visually impaired cohort could not be independently evaluated. No significant adverse effects of melatonin were reported in these excluded studies.

AUTHORS' CONCLUSIONS

There is currently no high quality data to support or refute the use of melatonin for sleep disorders in visually impaired children. Placebo-controlled trials examining important clinical outcomes such as sleep quality, sleep latency, duration of sleep and night-time awakenings are needed. As the numbers of children meeting study inclusion criteria are likely to be low at individual sites, multicentre collaboration between developmental paediatricians, sleep physicians and other health care professionals is essential to achieve sufficient sample size for controlled studies. Such collaboration would help facilitate local recruitment at multiple sites, with study oversight being provided by paediatricians with expertise in sleep disorders. Participation of collaborators with experience in evidence-based practice research is also desirable due to the lack of protocols on melatonin therapy in the target population.

Evaluation of melatonin on the precocious puberty: a pilot study

OBJECTIVE

To evaluate the effect of 6-sulphatoxymelatonin on the sleep quality of girls with precocious puberty.

STUDY DESIGN

Ninety-nine girls were divided into three groups: GI, precocious puberty; GII, normal prepubescent; GIII, normal puberty. Questionnaires containing demographic and clinical data were applied. Blood was collected for hormonal evaluation for 6-sulphatoxymelatonin. The modified Rush Sleep Diary was used.

RESULTS

The levels of 6-sulphatoxymelatonin were highest in the group without pubertal development (75.23 ± 10.84 ng/ml), second highest in the group with normal puberty (45.66 ± 3.87 ng/ml, p < 0.001) and lowest in the group with true precocious puberty (37.04 ± 5.47 ng/ml). The amount of day sleep was greater in the group without pubertal development compared to other groups.

CONCLUSION

Despite the sleep data, melatonin may be involved in the precocious puberty process.

A systematic, updated review on the antidepressant agomelatine focusing on its melatonergic modulation

Objective:

To present an updated, comprehensive review on clinical and pre-clinical studies on agomelatine.

Method:

A MEDLINE, Psycinfo and Web of Science search (1966-May 2009) was performed using the following keywords: agomelatine, melatonin, S20098, efficacy, safety, adverse effect, pharmacokinetic, pharmacodynamic, major depressive disorder, bipolar disorder, Seasonal Affective Disorder (SAD), Alzheimer, ADHD, Generalized Anxiety Disorder (GAD), Panic Disorder (PD), Obsessive-Compulsive Disorder (OCD), anxiety disorders and mood disorder.

Study collection and data extraction:

All articles in English identified by the data sources were evaluated. Randomized, controlled clinical trials involving humans were prioritized in the review. The physiological bases of melatonergic transmission were also examined to deepen the clinical comprehension of agomelatine’ melatonergic modulation.

Data synthesis:

Agomelatine, a melatonergic analogue drug acting as MT₁/MT₂ agonist and 5-HT_2C antagonist, has been reported to be an effective antidepressant therapy.

Conclusions:

Although a bias in properly assessing the “sleep core” of depression may still exist with current screening instruments, therefore making difficult to compare agomelatine’ efficacy to other antidepressant ones, comparative studies showed agomelatine to be an intriguing option for depression and, potentially, for other therapeutic targets as well.

Melatonin in children with autistic spectrum disorders: recent and practical data

Over the last 20 years, melatonin, a pineal hormone synthesized from serotonin, has been implicated in various studies on the autism spectrum disorder (ASD) and altered melatonin levels were detected in subgroups of subjects with ASD. Its effect on sleep disturbances got the attention of clinicians and several investigations were carried out to determine the usefulness and safety of melatonin administration in this disorder. Hypotheses were also raised regarding the possibility that the dysfunctional synthesis and secretion of melatonin detected in subgroups of subjects with ASD may increase the risk as well the severity of ASD. The purpose of this paper is to review our pharmacokinetic knowledge on melatonin and present results from recent studies on sleep disorders in autism, their treatment with melatonin and the impact of melatonin prescription in children with ASD evaluated in a Diagnostic Center for Autism Spectrum Disorder in Paris, France.

Sleep interventions for the treatment of depression

Sleep disturbances are common in depressed patients. Insomnia may predate the onset of major depression, increases the likelihood of a depressive relapse, and is associated with an impaired response to treatment. Benzodiazepine drugs may have inherent antidepressant effects; thus, these and other sedative-hypnotic drugs can be beneficial for treating insomnia in depressed patients and may enhance the overall effectiveness of antidepressant drugs. Sedating antidepressant drugs are used for treating primary insomnia, but their sleep-promoting effects have been demonstrated primarily in depressed patients. Several second-generation antipsychotic drugs are used in low doses to promote sleep, but they also have inherent antidepressant effects. Cognitive-behavioral therapy targeting insomnia can effectively enhance the response to antidepressant medication. Sleep deprivation, which is also associated with a transient antidepressant effect, is difficult to use in routine clinical practice but might be an appropriate strategy for treatment-resistant forms of depression.

Therapeutic armamentarium for treating depression

Depressive disorders are highly prevalent and are a leading cause of disability, morbidity, and mortality worldwide; however, they often remain undertreated or untreated. This article provides a broad overview of the many strategies for treating depression. More than 24 antidepressant medications and depression-focused psychotherapies are available as first-choice options for treating depression. When patients have not had a satisfactory treatment response, the 2 main strategies are switching to an alternative antidepressant therapy or adding a second antidepressant therapy. A large number of medication combinations have been reported in the literature, and some have been shown to be effective in controlled studies. Nonstandard alternatives to conventional antidepressant treatments include exercise, light therapy, sleep deprivation, and various complementary and alternative therapies. For more chronic and refractory forms of depression, various neuromodulation therapies are available or are being investigated. Because depressive disorders are common in primary care and other medical settings, medical practitioners should be aware of the therapeutic armamentarium available for treating depression.

Altered sleep architecture and higher incidence of subsyndromal depression in low endogenous melatonin secretors

Melatonin secretion is synchronized to the sleep/wake cycle and has been suggested to have somnogenic properties. Sleep/wake cycle disruption and alterations in the secretary pattern of melatonin is present in various psychiatric disorders. The objective of this study was to investigate the sleep architecture and the presence of depression in individuals with low endogenous melatonin levels. The study included 16 participants (mean age 30.3 +/- 14.9 years). The first night of testing included psychiatric evaluation followed by melatonin secretion profile evaluation by Dim Light Melatonin Onset test and then standard montage polysomnographic testing. On the second night, only polysomnographic testing was carried out with an imposed sleep period of 8 h. Low endogenous melatonin secretors (LEMS) showed no discernible peaks in melatonin secretion compared to normal secretors (controls). LEMS demonstrated significant alterations in rapid eye movement sleep but not in non-rapid eye movement sleep along with poor sleep initiation and quality compared to controls. 55.6% of the low melatonin secretors group presented with subsyndromal depression. Melatonin has significant bearing on sleep architecture and a lack of melatonin may desynchronize endogenous rhythms allowing subsyndromal depression to manifest.

Epidemiology and management of insomnia in children with autistic spectrum disorders

Insomnia is the predominant sleep concern in children with autistic spectrum disorder (ASD), and its nature is most likely multifactorial, with neurochemical (abnormalities in serotonergic transmission or melatonin levels), psychiatric (anxiety), and behavioral (poor sleep habits) etiological factors involved. Children with ASD experience sleep problems similar to those of typically developing children, although the prevalence is markedly higher, occurring in 44-83% of school-aged children with ASD. Caregivers usually report that insomnia is the most frequent sleep disorder, described as disorders of initiating and maintaining sleep, restless sleep, bedtime resistance, co-sleeping, alterations of sleep hygiene, and early awakenings in the morning. Many actigraphic studies have added information on sleep disorders, confirming the questionnaire findings in the majority of cases. There are relatively few polysomnographic data for ASD, compared with questionnaire studies, and most of these studies reported a reduction in total sleep time and more undifferentiated sleep in the youngest patients. These findings were associated with several sleep microstructure alterations during rapid eye movement (REM) sleep, and with non-REM (NREM) sleep microstructure changes that appeared to be related to cognitive impairment rather than to the autistic core. Moreover, few data about other less frequent sleep disorders, such as periodic limb movements disorder and obstructive sleep apnea syndrome, bruxism, and the influence of epilepsy and EEG abnormalities, are available. Both pharmacologic and behavioral interventions have been suggested for the treatment of sleep problems in autistic children. The most common types of behavioral interventions are complete extinction (removing reinforcement to reduce a behavior) and various forms of graduated extinction. Melatonin has shown promising results in the treatment of insomnia in children with ASD. Although controlled studies are limited, there are more data demonstrating the safety and effectiveness of melatonin in ASD than for other sedative/hypnotic drugs. Finally, a dual treatment for insomnia in ASDs with melatonin and behavioral techniques has been suggested. A recent study using a combination of genetic and functional experimental techniques reported evidence that low melatonin concentration caused by a primary deficit in acetylserotonin methyltransferase activity is a risk factor for ASD. Sleep problems usually start at the same age as developmental regression, suggesting a higher vulnerability at this period of life. Further studies, beginning at younger ages, are necessary to better investigate these aspects and the role of melatonin in insomnia in children with ASD.

Melatonin Treatment for Insomnia in Pediatric Patients with Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

To evaluate the efficacy and safety of melatonin for the treatment of insomnia in pediatric patients with attention-deficit/hyperactivity disorder (ADHD).

DATA SOURCES

Literature was accessed through MEDLINE (1948-August 2009), EMBASE (1950-August 2009), and Scopus (1960-August 2009) using the terms melatonin, attention-deficit/hyperactivity disorder (ADHD), pediatric, insomnia, sleep disorder, and sleep. In addition, reference citations from publications identified were reviewed for relevant information.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles and human studies were identified and evaluated. Results from all identified randomized trials (n = 5), safety studies (n = 1), long-term follow-up studies (n = 1), post hoc retrospective analyses (n = 1), meta-analyses (n = 2), review articles (n = 9), and letters (n = 1) were summarized.

DATA SYNTHESIS

Pediatric insomnia is prevalent in children with ADHD and impacts academic performance, social functioning, overall health, and family life. First-line therapy includes ruling out differential diagnoses, optimizing ADHD stimulant treatment, and initiating good sleep hygiene and behavioral therapy. Adjuvant pharmacotherapy is then an option and melatonin is often prescribed. Melatonin regulates circadian rhythm sleep disorders such as sleep-onset insomnia (SOI) in children with ADHD. Four studies in children with ADHD and insomnia showed improvement in sleep onset and sleep latency. Studies included children 6–14 years old and melatonin doses ranged from 3 to 6 mg administered within a few hours of a scheduled bedtime. In all studies, adverse events were transient and mild. The available melatonin studies are limited by small size and short duration; variable SOI criteria, ADHD criteria, and treatment assessments; and lack of generalizability.

CONCLUSIONS

Available data suggest that melatonin is a well-tolerated and efficacious treatment option for pediatric patients with chronic SOI and ADHD. Regulated melatonin products and larger, well-designed trials to establish optimal dosing regimens and long-term safety are needed.

Dose finding of melatonin for chronic idiopathic childhood sleep onset insomnia: an RCT

RATIONALE

Pharmacokinetics of melatonin in children might differ from that in adults.

OBJECTIVES

This study aims to establish a dose-response relationship for melatonin in advancing dim light melatonin onset (DLMO), sleep onset (SO), and reducing sleep onset latency (SOL) in children between 6 and 12 years with chronic sleep onset insomnia (CSOI).

METHODS

The method used for this study is the randomized, placebo-controlled double-blind trial. Children with CSOI (n = 72) received either melatonin 0.05, 0.1, and 0.15 mg/kg or placebo during 1 week. Sleep was assessed with log and actigraphy during this week and the week before. Outcomes were the shifts in DLMO, SO, and SOL.

RESULTS

Treatment with melatonin significantly advanced SO and DLMO by approximately 1 h and decreased SOL by 35 min. Within the three melatonin groups, effect size was not different, but the circadian time of administration (TOA) correlated significantly with treatment effect on DLMO (r (s) = -0.33, p = 0.022) and SO (r (s) = -0.38, p = 0.004), whereas clock TOA was correlated with SO shift (r = -0.35, p = 0.006) and not with DLMO shift.

CONCLUSIONS

No dose-response relationship of melatonin with SO, SOL, and DLMO is found within a dosage range of 0.05-0.15 mg/kg. The effect of exogenous melatonin on SO, SOL, and DLMO increases with an earlier circadian TOA. The soporific effects of melatonin enhance the SO shift. This study demonstrates that melatonin for treatment of CSOI in children is effective in a dosage of 0.05 mg/kg given at least 1 to 2 h before DLMO and before desired bedtime.

Critical appraisal of ramelteon in the treatment of insomnia

Ramelteon is the first member of a novel class of hypnotics and acts as a selective melatonin receptor agonist. In 2005, ramelteon was approved by the US Food and Drug Administration for the treatment of insomnia characterized by sleep onset problems. Its unique mechanism of action made it a promising candidate compared with the widely used hypnotics that act on the benzodiazepine receptor complex. Several studies have examined its efficacy and safety as a hypnotic agent. The primary efficacy of ramelteon was found to lie in a decrease in latency to persistent sleep, as measured by polysomnographic tests. Other sleep-related measures, such as total sleep time and number of nightly awakenings, show less pronounced improvement when treated with ramelteon. In addition, no rebound insomnia or abuse potential was observed in clinical studies. Although additional studies are necessary, current data on the acute and next-morning effects of ramelteon did not indicate cognitive or psychomotor impairment. Overall, ramelteon is safe and well tolerated, although some questions remain regarding its long-term efficacy and safety. These issues and possibilities for use in other patient groups should be addressed in future research.

Critical appraisal and update on the clinical utility of agomelatine, a melatonergic agonist, for the treatment of major depressive disease in adults

This article describes the pharmacology of the novel atypical antidepressant drug agomelatine, critically reviews and evaluates its clinical use for the treatment of major depression, and suggests areas for further research. Agomelatine is a synthetic analog of the hormone melatonin. It stimulates the activity of melatonin MT1 and MT2 receptors and inhibits the activity of serotonin 5HT-2C receptor subtypes. Three acute trials demonstrated clinically modest, but statistically significant benefits over placebo. Three acute trials did not find agomelatine more effective than placebo. A meta-analysis of these six trials demonstrated a small, statistically significant, marginally clinically relevant difference between agomelatine and placebo. The only placebo-controlled study in elderly patients did not demonstrate a significant benefit for agomelatine. It was more effective than placebo in only one of two relapse prevention studies. Agomelatine was generally well tolerated compared to placebo. Its side-effect profile is different than and compares favorably to other antidepressant drugs. The overall tolerability of agomelatine in head-to-head comparisons was not substantially better than active drug comparators. Agomelatine is contraindicated in patients with impaired liver function and in patients taking drugs that potently inhibit CYP-1A2 metabolic enzymes. Because elevated liver enzymes are common, and there is a rare risk of more serious liver reactions, routine laboratory monitoring of liver function is recommended periodically throughout treatment. Agomelatine does not have clinically significant advantages compared to other antidepressant drugs, and it has certain limitations and disadvantages. Because of its unique pharmacology and relatively benign tolerability profile, however, it may be a useful alternative for patients who do not respond to or cannot tolerate other antidepressant drugs.

Pineal volume and circadian melatonin profile in healthy volunteers: an interdisciplinary approach

PURPOSE

To correlate pineal parenchyma volume (PP) to circadian melatonin profiles and to determine the 24-hour melatonin per volume of pineal tissue (MLPV). Furthermore, we compared melatonin profiles of cystic and solid glands.

METHODS

In 15 healthy male subjects (20-27 years) the PP was determined using high-resolution magnetic resonance imaging (trueFISP, isotropic voxel: 0.8 mm(3)). Melatonin plasma concentrations (MC) were determined every 2 hours for 24 hours.

RESULTS

Mean PP was 125 +/- 54 mm(3). PP correlated linearly to maximum MC and to 24-hour melatonin (r = 0.61 and r = 0.64, P < 0.05) but not to minimum MC. The 24-hour melatonin was 653 +/- 242.6 pg/mL, MLPV was 5.8 +/- 2.3 pg/mL*ml(-1). Nine pineal glands were solid and six were cystic. PP of solid glands showed higher linear correlations to maximum melatonin, to 24-hour melatonin, and to the slope of the melatonin increase of the curve (P < 0.05).

CONCLUSION

PP correlates linearly to melatonin plasma concentrations in humans. MLPV displays similar interindividual differences as 24-hour melatonin. PP of solid glands show better correlation to melatonin profiles than cystic.

Good night and good luck: norepinephrine in sleep pharmacology

Sleep is a crucial biological process that is regulated through complex interactions between multiple brain regions and neuromodulators. As sleep disorders can have deleterious impacts on health and quality of life, a wide variety of pharmacotherapies have been developed to treat conditions of excessive wakefulness and excessive sleepiness. The neurotransmitter norepinephrine (NE), through its involvement in the ascending arousal system, impacts the efficacy of many wake- and sleep-promoting medications. Wake-promoting drugs such as amphetamine and modafinil increase extracellular levels of NE, enhancing transmission along the wake-promoting pathway. GABAergic sleep-promoting medications like benzodiazepines and benzodiazepine-like drugs that act more specifically on benzodiazepine receptors increase the activity of GABA, which inhibits NE transmission and the wake-promoting pathway. Melatonin and related compounds increase sleep by suppressing the activity of the neurons in the brain's circadian clock, and NE influences the synthesis of melatonin. Antihistamines block the wake-promoting effects of histamine, which shares reciprocal signaling with NE. Many antidepressants that affect the signaling of NE are also used for treatment of insomnia. Finally, adrenergic receptor antagonists that are used to treat cardiovascular disorders have considerable sedative effects. Therefore, NE, long known for its role in maintaining general arousal, is also a crucial player in sleep pharmacology. The purpose of this review is to consider the role of NE in the actions of wake- and sleep-promoting drugs within the framework of the brain arousal systems.

Pharmacologic treatment of pediatric insomnia

Pediatric insomnia is common in children and adolescents, particularly in children who have comorbid medical, psychiatric, and neurodevelopmental disorders, and may be associated with cognitive, emotional, and psychosocial impairments that often result in significant caregiver burden. Although several behavioral interventions for pediatric insomnia are effective, there is a relative paucity of empiric evidence supporting the use of pharmacologic treatment. Sedative/hypnotic drugs are frequently used in clinical practice to treat pediatric insomnia, and guidelines for the use of these medications in general as well as for specific medications have been developed. This review presents expert consensus guidelines for the use of these medications in clinical practice, with a focus on the different classes of pharmacologic agents that are most commonly prescribed.

Approaches to measuring the effects of wake-promoting drugs: a focus on cognitive function

OBJECTIVES

In clinical drug development, wakefulness and wake-promotion may be assessed by a large number of scales and questionnaires. Objective assessment of wakefulness is most commonly made using sleep latency/maintenance of wakefulness tests, polysomnography and/or behavioral measures. The purpose of the present review is to highlight the degree of overlap in the assessment of wakefulness and cognition, with consideration of assessment techniques and the underlying neurobiology of both concepts.

DESIGN

Reviews of four key areas were conducted: commonly used techniques in the assessment of wakefulness; neurobiology of sleep/wake and cognition; targets of wake promoting and/or cognition enhancing drugs; and ongoing clinical trials investigating wake promoting effects.

RESULTS

There is clear overlap between the assessment of wakefulness and cognition. There are common techniques which may be used to assess both concepts; aspects of the neurobiology of both concepts may be closely related; and wake-promoting drugs may have nootropic properties (and vice versa). Clinical trials of wake-promoting drugs often, though not routinely, assess aspects of cognition.

CONCLUSIONS

Routine and broad assessment of cognition in the development of wake-promoting drugs may reveal important nootropic effects, which are not secondary to alertness/wakefulness, whilst existing cognitive enhancers may have underexplored or unknown wake promoting properties.

Sleep problems in autism spectrum disorders: prevalence, nature, & possible biopsychosocial aetiologies

As considerably more people are diagnosed with an autism spectrum disorder (ASD), interest in the associated behaviours, including sleep problems has increased. This has resulted in a subsequent increase in the research related to the sleep problems occurring in people with an ASD. This article summarizes and evaluates the current literature related to a) the higher prevalence of a sleep problem compared to typically developing children, b) the specific types of sleep problems for people with an ASD, and c) the possible aetiology of sleep problems in the ASDs within a biopsychosocial framework. It is concluded that recent studies confirm that the majority of this population are likely to experience sleep difficulties, with settling issues in children with an ASD the most commonly reported. However, exploration of the types of sleep difficulties and associated aetiological factors in the ASDs is still in its infancy.

Microtubules modulate melatonin receptors involved in phase-shifting circadian activity rhythms: in vitro and in vivo evidence

MT1 melatonin receptors expressed in Chinese hamster ovary (CHO) cells remain sensitive to a melatonin re-challenge even following chronic melatonin exposure when microtubules are depolymerized in the cell, an exposure that normally results in MT1 receptor desensitization. We extended our findings to MT2 melatonin receptors using both in vitro and in vivo approaches. Using CHO cells expressing human MT2 melatonin receptors, microtubule depolymerization prevents the loss in the number of high potency states of the receptor when compared to melatonin-treated cells. In addition, microtubule depolymerization increases melatonin-induced PKC activity but not PI hydrolysis via Gi proteins similar to that shown for MT1Rs. Furthermore, microtubule depolymerization in MT2-CHO cells enhances the exchange of GTP on Gi-proteins using a photoaffinity analog of GTP. To test whether microtubules are capable of modulating melatonin-induced phase-shifts, microtubules are depolymerized specifically within the suprachiasmatic nucleus of the hypothalamus (SCN) of the Long Evans rat and the efficacy of melatonin to phase shift their circadian activity rhythms was assessed and compared to animals with intact SCN microtubules. We find that microtubule depolymerization in the SCN using either Colcemid or nocodazole enhances the efficacy of 10 pm melatonin to phase-shift the activity rhythms of the Long Evans rat. No enhancement occurs in the presence of beta-lumicolchicine, the inactive analog of Colcemid. Taken together, these data suggest that microtubule dynamics can modulate melatonin-induced phase shifts of circadian activity rhythms which may explain, in part, why circadian disturbances occur in individuals afflicted with diseases associated with microtubule disturbances.

Melatonin and breast cancer: cellular mechanisms, clinical studies and future perspectives

Recent studies have suggested that the pineal hormone melatonin may protect against breast cancer, and the mechanisms underlying its actions are becoming clearer. Melatonin works through receptors and distinct second messenger pathways to reduce cellular proliferation and to induce cellular differentiation. In addition, independently of receptors melatonin can modulate oestrogen-dependent pathways and reduce free-radical formation, thus preventing mutation and cellular toxicity. The fact that melatonin works through a myriad of signalling cascades that are protective to cells makes this hormone a good candidate for use in the clinic for the prevention and/or treatment of cancer. This review summarises cellular mechanisms governing the action of melatonin and then considers the potential use of melatonin in breast cancer prevention and treatment, with an emphasis on improving clinical outcomes.