Sleep disorders and melatonin rhythms in elderly people

Therapeutic effects of melatonin receptor agonists on sleep and comorbid disorders

Several melatonin receptors agonists (ramelteon, prolonged-release melatonin, agomelatine and tasimelteon) have recently become available for the treatment of insomnia, depression and circadian rhythms sleep-wake disorders. The efficacy and safety profiles of these compounds in the treatment of the indicated disorders are reviewed. Accumulating evidence indicates that sleep-wake disorders and co-existing medical conditions are mutually exacerbating. This understanding has now been incorporated into the new Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). Therefore, when evaluating the risk/benefit ratio of sleep drugs, it is pertinent to also evaluate their effects on wake and comorbid condition. Beneficial effects of melatonin receptor agonists on comorbid neurological, psychiatric, cardiovascular and metabolic symptomatology beyond sleep regulation are also described. The review underlines the beneficial value of enhancing physiological sleep in comorbid conditions.

Melatonin ameliorates cognitive impairment induced by sleep deprivation in rats: role of oxidative stress, BDNF and CaMKII

Sleep deprivation (SD) has been shown to induce oxidative stress which causes cognitive impairment. Melatonin, an endogenous potent antioxidant, protects neurons from oxidative stress in many disease models. The present study investigated the effect of melatonin against SD-induced cognitive impairment and attempted to define the possible mechanisms involved. SD was induced in rats using modified multiple platform model. Melatonin (15 mg/kg) was administered to the rats via intraperitoneal injection. The open field test and Morris water maze were used to evaluate cognitive ability. The cerebral cortex (CC) and hippocampus were dissected and homogenized. Nitric oxide (NO) and malondialdehyde (MDA) levels and the superoxide dismutase (SOD) enzyme activity of hippocampal and cortical tissues (10% wet weight per volume) were performed to determine the level of oxidative stress. The expression of brain-derived neurotrophic factor (BDNF) and calcium-calmodulin dependent kinase II (CaMKII) proteins in CC and hippocampus was assayed by means of immunohistochemistry. The results revealed that SD impairs cognitive ability, while melatonin treatment prevented these changes. In addition, melatonin reversed SD-induced changes in NO, MDA and SOD in both of the CC and hippocampus. The results of immunoreactivity showed that SD decreased gray values of BDNF and CaMKII in CC and hippocamal CA1, CA3 and dentate gyrus regions, whereas melatonin improved the gray values. In conclusion, our results suggest that melatonin prevents cognitive impairment induced by SD. The possible mechanism may be attributed to its ability to reduce oxidative stress and increase the levels of CaMKII and BDNF in CC and hippocampus.

A Jerte valley cherry product provides beneficial effects on sleep quality. Influence on aging

OBJECTIVE

In the present work, we evaluated the effect of the intake of a Jerte Valley cherry-based product (JVCP), compared to a placebo product, on sleep quality, urinary 6-sulfatoxymelatonin (aMT6-s) levels and the serum concentration of interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α) and interleukin-8 (IL-8).

DESIGN

This was a blind, placebo-controlled, randomized, crossover study.

SETTING

University of Extremadura (Spain).

PARTICIPANTS

Ten young (20-30 years old), ten middle-aged (35-55 years old), and ten elderly (65-85 years old) participants.

INTERVENTION

A placebo (Kool-Aid®) or JVCP (patent no. ES 2342141 B1) were consumed twice a day, as lunch and dinner desserts.

MEASUREMENTS

Actigraphic monitoring was used to record and display the temporal patterns of the individuals' activity and rest. Urinary aMT6-s and serum cytokines (IL-1β, TNF-α and IL-8) were also determined.

RESULTS

The consumption of the JVCP improved the nocturnal rest, measured by sleep efficiency, number of awakenings, total nocturnal activity, sleep latency, assumed sleep, actual sleep time and immobility. Moreover, it was detected an increase in both the levels of aMT6-s found in first-void morning urine and the concentrations of serum pro-somnogenic cytokines obtained from samples collected at the acrophase of the melatonin rhythm (1.00 am) in all experimental age groups after the JVCP consumption. Generally, better results were obtained with advancing age.

CONCLUSION

The ingestion of the JVCP may contribute to establish a high-quality sleep and be used as a potential nutraceutical tool to prevent sleep disorders with the advance of age.

Management of anxiety and sleep disorders: role of complementary and alternative medicine and challenges of integration with conventional orthodox care

There is renewed attention and greater focus on anxiety and sleep- sleep-related disturbances because of the high prevalence, complexity, and their health related implications. The role of complementary and alternative medicine (CAM), which refers to therapeutic approaches that are "complementary to the end goals of decreasing illness and enhancing wellness, but are alternative to conventional medical treatment" is also increasingly recognized. In this review, we considered CAM approach to the management of anxiety and sleep disorders and discussed a few challenges associated with the effective integration of alternative therapy with conventional orthodox medical care.

Polymorphisms in the melatonin receptor 1B gene and the risk of delirium

BACKGROUND/AIMS

A disturbed sleep-wake rhythm cycle can be seen in delirium and as melatonin regulates this cycle via melatonin receptors, genetic variations in these receptors may contribute to susceptibility to delirium. The purpose of this study was to investigate whether genetic variants in the melatonin receptor 1B (MTNR1B) gene are associated with delirium.

METHODS

Elderly medical and hip surgery patients were included in the study. Five single-nucleotide polymorphisms (SNPs) were determined in the MTNR1B gene, i.e. rs18030962, rs3781638, rs10830963, rs156244 and rs4753426.

RESULTS

In total, 53% of 171 hip fracture patients and 33% of 699 medical patients were diagnosed with delirium. None of the polymorphisms were found to be associated with the occurrence of delirium.

CONCLUSION

Future research could focus on sequencing this gene to look for other functional SNPs in relation to delirium.

Age-related changes in neuroendocrine rhythmic function in the rhesus macaque

Many environmental conditions show rhythmic changes across the 24-h day; these include changes in light intensity, ambient temperature, food availability, and presence or absence of predators. Consequently, many organisms have developed corresponding adaptations, which ensure that specific physiological and behavioral events occur at an appropriate time of the day. In mammals, the underlying mechanism responsible for synchronizing internal biochemical processes with circadian environmental cues has been well studied and is thought to comprise three major components: (1) photoreception by the retina and transmission of neural signals along the retinohypothalamic tract, (2) integration of photoperiodic information with an internal reference circadian pacemaker located in the suprachiasmatic nucleus, and (3) dissemination of circadian information to target organs, via the autonomic nervous system and through humoral pathways. Given the importance that neuroendocrine rhythms play in coordinating normal circadian physiology and behavior, it is plausible that their perturbation during aging contributes to the etiology of age-related pathologies. This mini-review highlights some of the most dramatic rhythmic neuroendocrine changes that occur in primates during aging, focusing primarily on data from the male rhesus macaques (Macaca mulatta). In addition to the age-associated attenuation of hormone levels and reduction of humoral circadian signaling, there are also significant age-related changes in intracrine processing enzymes and hormone receptors which may further affect the functional efficacy of these hormones. Rhesus macaques, like humans, are large diurnal primates and show many of the same physiological and behavioral circadian changes during aging. Consequently, they represent an ideal translational animal model in which to study the causes and consequences of age-associated internal circadian disruption and in which to evaluate novel therapies.

Melatonin treatment in children with therapy-resistant monosymptomatic nocturnal enuresis

OBJECTIVE

To evaluate the effects of exogenous melatonin on the frequency of wet nights, on the sleep-wake cycle, and on the melatonin profile in children with therapy-resistant MNE.

PATIENTS AND METHODS

24 patients were included. Patients had to maintain a diary including time of sleep and arousal, and whether they had a dry or a wet bed in the morning. We measured baseline melatonin profiles in saliva. Hereafter, patients were randomized to synthetic melatonin or placebo. After 3 and 6 months we evaluated the frequency of enuresis and the melatonin profiles.

RESULTS

11 patients were randomized to melatonin, 13 to placebo. We evaluated melatonin profiles of 7 patients in the melatonin group and of 8 in the placebo group. We observed a change in profile in the melatonin group, but we did not observe a difference in the sleep-wake cycle or the frequency of wet nights in either group.

CONCLUSION

This is the first time exogenous melatonin has been evaluated in the treatment of MNE. Although we observed a change in melatonin profile after the use of exogenous melatonin, we did not observe a change in enuresis frequency or in the sleep-wake cycle of this select group of patients.

Prevalence of sleep disturbances, disorders, and problems following traumatic brain injury: a meta-analysis

BACKGROUND

Sleep is often disrupted following a traumatic brain injury (TBI), which may compromise recovery and quality of life. Prevalence rates vary widely, reflecting differences in the criteria and measures that are used to assess sleep, as well as sample differences. This meta-analysis examined the prevalence of general and specific, and formally and informally diagnosed, sleep disturbances following TBI in order to establish the nature and extent of these sequelae and their potential impact on recovery.

METHODS

Data from 21 studies, which assessed (1) sleep disturbances, regardless of type or severity, (2) diagnosed sleep disorders, and (3) specific sleep problems following TBI, were analyzed and compared to data for the general population.

RESULTS

Overall, 50% of people suffered from some form of sleep disturbance after a TBI and 25-29% had a diagnosed sleep disorder (insomnia, hypersomnia, apnea) - rates that are much higher than those seen in the general population. They were also two to four times more likely to experience problems with sleep maintenance and efficiency, nightmares, excessive sleepiness, early awakenings, and sleep walking.

CONCLUSION

Sleep disturbances are very common after TBI and have the potential to seriously undermine patient rehabilitation, recovery, and outcomes; making it important to routinely screen for such problems in order to assess both treatment needs and their potential impact on recovery and outcome.

Drugs for insomnia

INTRODUCTION

Sleep is a vital neurochemical process involving sleep-promoting and arousal centers in the brain. Insomnia is a pervasive disorder characterized by difficulties in initiating or maintaining or non-refreshing (poor quality) sleep and clinically significant daytime distress. Insomnia is more prevalent in women and old age and puts sufferers at significant physical and mental health risks. This review summarizes published data on the current and emerging insomnia drug classes, rationale for development and associated risks/benefits. (Summary of Product Characteristics and Medline search on "hypnotic" or specific drug names and "Insomnia").

AREAS COVERED

GABA(A) receptor modulators facilitate sleep onset and some improve maintenance but increase risk of dependence, memory, cognitive and psychomotor impairments, falls, accidents and mortality. Melatonin receptor agonists improve quality of sleep and/or sleep onset but response may develop over several days. They have more benign safety profiles and are indicated for milder insomnia, longer usage and (prolonged release melatonin) older patients. Histamine H-1 receptor antagonists improve sleep maintenance but their effects on cognition, memory and falls remain to be demonstrated. Late-stage pipeline orexin OX1/OX2 and serotonin 5HT2A receptor antagonists may hold the potential to address several unmet needs in insomnia pharmacotherapy but safety issues cast some doubts over their future.

EXPERT OPINION

Current and new insomnia drugs in the pipeline target different sleep regulating mechanisms and symptoms and have different tolerability profiles. Drug selection would ideally be based on improvement in the quality of patients' sleep, overall quality of life and functional status weighed against risk to the individual and public health.

Pharmacotherapy of insomnia

INTRODUCTION

Insomnia is one of the most prevalent sleep disorders in developed countries, being surpassed only by chronic sleep deprivation. Patients with insomnia tend to have an altered quality of life, impaired daytime functioning and an increased risk of work accidents and motor vehicle crashes. Insomnia is commonly associated with chronic medical conditions, metabolic illnesses and mental disorders (such as depression and anxiety), with which there is a dual, reciprocal relationship.

AREAS COVERED

This paper focuses on current pharmacotherapy options for the treatment of insomnia, particularly benzodiazepine receptor agonists, which nowadays represent the mainstay of hypnotic therapy. The melatonin receptor antagonist, ramelteon, is reviewed (an alternative for some patients with only sleep-onset difficulty), as are sedating antidepressants, which are commonly used 'off-label' to treat insomnia, despite limited efficacy data and potential significant safety concerns. Orexin (OX) antagonists are also discussed, especially those that block OX2 or both OX1 and OX2 receptors, as these are the most promising new agents for the treatment of insomnia, with encouraging results in preliminary clinical trials.

EXPERT OPINION

Research to evaluate and formulate treatments for insomnia is often complicated by the fact that insomnia is usually of multifactorial etiology. Understanding the molecular and receptor mechanisms involved in promoting sleep in varied disorders could provide future approaches in new drug development. In the long term, more randomized controlled trials are needed to assess both short-term and long-term effects of these medications and their efficacy in comorbid diseases that affect sleep quality or quantity.

Neurobiology, pathophysiology, and treatment of melatonin deficiency and dysfunction

Melatonin is a highly pleiotropic signaling molecule, which is released as a hormone of the pineal gland predominantly during night. Melatonin secretion decreases during aging. Reduced melatonin levels are also observed in various diseases, such as types of dementia, some mood disorders, severe pain, cancer, and diabetes type 2. Melatonin dysfunction is frequently related to deviations in amplitudes, phasing, and coupling of circadian rhythms. Gene polymorphisms of melatonin receptors and circadian oscillator proteins bear risks for several of the diseases mentioned. A common symptom of insufficient melatonin signaling is sleep disturbances. It is necessary to distinguish between symptoms that are curable by short melatonergic actions and others that require extended actions during night. Melatonin immediate release is already effective, at moderate doses, for reducing difficulties of falling asleep or improving symptoms associated with poorly coupled circadian rhythms, including seasonal affective and bipolar disorders. For purposes of a replacement therapy based on longer-lasting melatonergic actions, melatonin prolonged release and synthetic agonists have been developed. Therapies with melatonin or synthetic melatonergic drugs have to consider that these agents do not only act on the SCN, but also on numerous organs and cells in which melatonin receptors are also expressed.

Melatonin and its analogs in insomnia and depression

Benzodiazepine sedative-hypnotic drugs are widely used for the treatment of insomnia. Nevertheless, their adverse effects, such as next-day hangover, dependence and impairment of memory, make them unsuitable for long-term treatment. Melatonin has been used for improving sleep in patients with insomnia mainly because it does not cause hangover or show any addictive potential. However, there is a lack of consistency on its therapeutic value (partly because of its short half-life and the small quantities of melatonin employed). Thus, attention has been focused either on the development of more potent melatonin analogs with prolonged effects or on the design of slow release melatonin preparations. The MT(1) and MT(2) melatonergic receptor ramelteon was effective in increasing total sleep time and sleep efficiency, as well as in reducing sleep latency, in insomnia patients. The melatonergic antidepressant agomelatine, displaying potent MT(1) and MT(2) melatonergic agonism and relatively weak serotonin 5HT(2C) receptor antagonism, was found effective in the treatment of depressed patients. However, long-term safety studies are lacking for both melatonin agonists, particularly considering the pharmacological activity of their metabolites. In view of the higher binding affinities, longest half-life and relative higher potencies of the different melatonin agonists, studies using 2 or 3mg/day of melatonin are probably unsuitable to give appropriate comparison of the effects of the natural compound. Hence, clinical trials employing melatonin doses in the range of 50-100mg/day are warranted before the relative merits of the melatonin analogs versus melatonin can be settled.

Older poor-sleeping women display a smaller evening increase in melatonin secretion and lower values of melatonin and core body temperature than good sleepers

Melatonin concentration and core body temperature (CBT) follow endogenous circadian biological rhythms. In the evening, melatonin level increases and CBT decreases. These changes are involved in the regulation of the sleep-wake cycle. Therefore, the authors hypothesized that age-related changes in these rhythms affect sleep quality in older people. In a cross-sectional study design, 11 older poor-sleeping women (aged 62-72 yrs) and 9 older good-sleeping women (60-82 yrs) were compared with 10 younger good-sleeping women (23-28 yrs). The older groups were matched by age and body mass index. Sleep quality was assessed by the Pittsburgh Sleep Quality Index questionnaire. As an indicator of CBT, oral temperature was measured at 1-h intervals from 17:00 to 24:00 h. At the same time points, saliva samples were collected for determining melatonin levels by enzyme-linked immunosorbent assay (ELISA). The dim light melatonin onset (DLMO), characterizing the onset of melatonin production, was calculated. Evening changes in melatonin and CBT levels were tested by the Friedman test. Group comparisons were performed with independent samples tests. Predictors of sleep-onset latency (SOL) were assessed by regression analysis. Results show that the mean CBT decreased in the evening from 17:00 to 24:00 h in both young women (from 36.57°C to 36.25°C, p < .001) and older women (from 36.58°C to 35.88°C, p < .001), being lowest in the older poor sleepers (p < .05). During the same time period, mean melatonin levels increased in young women (from 16.2 to 54.1 pg/mL, p < .001) and older women (from 10.0 to 23.5 pg/mL, p < .001), being lowest among the older poor sleepers (from 20:00 to 24:00 h, p < .05 vs. young women). Older poor sleepers also showed a smaller increase in melatonin level from 17:00 to 24:00 h than older good sleepers (mean ± SD: 7.0 ± 9.63 pg/mL vs. 15.6 ± 24.1 pg/mL, p = .013). Accordingly, the DLMO occurred at similar times in young (20:10 h) and older (19:57 h) good-sleeping women, but was delayed ∼50 min in older poor-sleeping women (20:47 h). Older poor sleepers showed a shorter phase angle between DLMO and sleep onset, but a longer phase angle between CBT peak and sleep onset than young good sleepers, whereas older good sleepers had intermediate phase angles (insignificant). Regression analysis showed that the DLMO was a significant predictor of SOL in the older women (R(2) = 0.64, p < .001), but not in the younger women. This indicates that melatonin production started later in those older women who needed more time to fall asleep. In conclusion, changes in melatonin level and CBT were intact in older poor sleepers in that evening melatonin increased and CBT decreased. However, poor sleepers showed a weaker evening increase in melatonin level, and their DLMO was delayed compared with good sleepers, suggesting that it is not primarily the absolute level of endogenous melatonin, but rather the timing of the circadian rhythm in evening melatonin secretion that might be related to disturbances in the sleep-wake cycle in older people.

Efficacy and safety of prolonged-release melatonin for insomnia in middle-aged and elderly patients with hypertension: a combined analysis of controlled clinical trials

BACKGROUND

Add-on prolonged-release melatonin (PRM) in antihypertensive therapy has been shown to ameliorate nocturnal hypertension. Hypertension is a major comorbidity among insomnia patients. The efficacy and safety of PRM for primary insomnia in patients aged 55 years and older who are treated with antihypertensive drugs were evaluated.

METHODS

Post hoc analysis of pooled antihypertensive drug-treated subpopulations from four randomized, double-blind trials of PRM and placebo for 3 weeks (N[PRM] = 195; N[placebo] = 197) or 28 weeks (N[PRM] = 157; N[placebo] = 40). Efficacy measurements included Leeds Sleep Evaluation Questionnaire scores of quality of sleep and alertness and behavioral integrity the following morning after 3 weeks, and sleep latency (daily sleep diary) and Clinical Global Impression of Improvement (CGI-I) after 6 months of treatment. Safety measures included antihypertensive drug-treated subpopulations from these four and three additional single-blind and open-label PRM studies of up to 1 year (N[PRM] = 650; N[placebo] = 632).

RESULTS

Quality of sleep and behavior following wakening improved significantly with PRM compared with placebo (P < 0.0001 and P < 0.0008, respectively). Sleep latency (P = 0.02) and CGI-I (P = 0.0003) also improved significantly. No differences were observed between PRM and placebo groups in vital signs, including daytime blood pressure at baseline and treatment phases. The rate of adverse events normalized per 100 patient-weeks was lower for PRM (3.66) than for placebo (8.53).

CONCLUSIONS

The findings demonstrate substantive and sustained efficacy of PRM in primary insomnia patients treated with antihypertensive drugs. PRM appears to be safe for insomnia in patients with cardiovascular comorbidity.

Mood disorders, circadian rhythms, melatonin and melatonin agonists

Recent advances in the understanding of circadian rhythms have led to an interest in the treatment of major depressive disorder with chronobiotic agents. Many tissues have autonomous circadian rhythms, which are orchestrated by the master clock, situated in the suprachiasmatic nucleus (SNC). Melatonin (N-acetyl-5-hydroxytryptamine) is secreted from the pineal gland during darkness. Melatonin acts mainly on MT1 and MT2 receptors, which are present in the SNC, regulating physiological and neuroendocrine functions, including circadian entrainment, referred to as the chronobiotic effet. Circadian rhythms has been shown to be either misaligned or phase shifted or decreased in amplitude in both acute episodes and relapse of major depressive disorder (MDD) and bipolar disorder. Manipulation of circadian rhythms either using physical treatments (such as high intensity light) or behavioral therapy has shown promise in improving symptoms. Pharmacotherapy using melatonin and pure melatonin receptor agonists, while improving sleep, has not been shown to improve symptoms of depression. A novel antidepressant, agomelatine, combines 5HT2c antagonist and melatonin agonist action, and has shown promise in both acute treatment of MDD and in preventing relapse.

Can cytogenetics explain the possible association between exposure to extreme low-frequency magnetic fields and Alzheimer's disease?

Recently, a number of epidemiological studies have suggested that occupational as well as residential exposure to extreme low-frequency electromagnetic fields (ELF-EMFs) may be a risk factor for Alzheimer's disease. This is not proven yet and there are no known biological mechanisms to explain this alleged association. Alzheimer's disease is characterized by a number of events that have, at least partially, a genetic origin. In particular, trisomy of chromosomes 17 and 21 seems to be involved. Overall ELF-EMFs have not been identified as genotoxic agents, but there are some papers in the scientific literature that indicate that they may enhance the effects of agents that are known to induce mutations or tumors. There are also some indications that ELF-EMFs may induce aneuploïdy. This opens some perspectives for investigating the alleged association between ELF-EMFs and Alzheimer's. This paper reviews the possibility of a cytogenetic association between the electromagnetic fields and Alzheimer's disease.

Prolonged-release melatonin for insomnia - an open-label long-term study of efficacy, safety, and withdrawal

Background

Prolonged-release melatonin (PRM) 2 mg is indicated for insomnia in patients aged 55 years and older. A recent double-blind placebo-controlled study demonstrated 6-month efficacy and safety of PRM in insomnia patients aged 18–80 and lack of withdrawal and rebound symptoms upon discontinuation.

Objective

To investigate the efficacy, safety, and withdrawal phenomena associated with 6–12 months PRM treatment.

Methods

Data from a prospective 6–12-month open-label study of 244 community dwelling adults with primary insomnia, who had participated in a placebo-controlled, double-blind dose-ranging trial of PRM. Patients received PRM nightly, followed by a 2-week withdrawal period. Main outcome measures were patient-reported sleep quality ratings (diary), adverse events, vital signs, and laboratory tests recorded at each visit, and withdrawal symptoms (CHESS-84 [Check-list Evaluation of Somatic Symptoms]). Nocturnal urinary 6-sulfatoxymelatonin excretion, a measure of the endogenous melatonin production, was assessed upon discontinuing long-term PRM.

Results

Of the 244 patients, 36 dropped out, 112 completed 6 months of treatment, and the other 96 completed 12 months of treatment. The mean number of nights by which patients reported sleep quality as “good” or “very good” was significantly higher during PRM than before treatment. There was no evidence of tolerance to PRM. Discontinuation of PRM was not associated with rebound insomnia or withdrawal symptoms; on the contrary, residual benefit was observed. PRM was well tolerated, and there was no suppression of endogenous melatonin production.

Conclusion

Results support the efficacy and safety of PRM in primary insomnia patients aged 20–80 throughout 6–12 months of continuous therapy. PRM discontinuation even after 12 months was not associated with adverse events, withdrawal symptoms, or suppression of endogenous melatonin production.

The effects of melatonin versus placebo on delirium in hip fracture patients: study protocol of a randomised, placebo-controlled, double blind trial

Background

With an ageing population, older persons become a larger part of the hospital population. The incidence of delirium is high in this group, and experiencing delirium has major short- and long-term sequelae, which makes prevention crucial. During delirium, a disruption of the sleep-wake cycle is frequently observed. Melatonin plays an important role in the regulation of the sleep-wake cycle, so this raised the hypothesis that alterations in the metabolism of melatonin might play an important role in the development of delirium. The aim of this article is to describe the design of a randomised, placebo controlled double-blind trial that is currently in progress and that investigates the effects of melatonin versus placebo on delirium in older, postoperative hip fracture patients.

Methods/Design

Acutely hospitalised patients aged 65 years or older admitted for surgical repair of hip fracture are randomised (n = 452) into a treatment or placebo group. Prophylactic treatment consists of orally administered melatonin (3 mg) at 21:00 h on five consecutive days. The primary outcome is the occurrence of delirium, to be diagnosed according to the Confusion Assessment Method, within eight days after start of the study medication. Secondary outcomes are delirium severity, measured by the Delirium Rating Scale; duration of delirium; differences in subtypes of delirium; differences in total length of hospital stay; total dose of antipsychotics and/or benzodiazepine use during delirium; and in-hospital complications. In the twelve-month follow up visit, cognitive function is measured by a Mini-Mental state examination and the Informant Questionnaire on Cognitive Decline in the Elderly. Functional status is assessed with the Katz ADL index score (patient and family version) and grip strength measurement. The outcomes of these assessments are compared to the outcomes that were obtained during admission.

Discussion

The proposed study will contribute to our knowledge because studies on the prophylactic treatment of delirium with long term follow up remain scarce. The results may lead to a prophylactic treatment for frail older persons at high risk for delirium that is safe, effective, and easily implementable in daily practice.

Trial registration

Dutch Clinical Trial Registry: NTR1576

Melatonin agonists in primary insomnia and depression-associated insomnia: are they superior to sedative-hypnotics?

Current pharmacological treatment of insomnia involves the use of sedative-hypnotic benzodiazepine and non-benzodiazepine drugs. Although benzodiazepines improve sleep, their multiple adverse effects hamper their application. Adverse effects include impairment of memory and cognitive functions, next-day hangover and dependence. Non-benzodiazepines are effective for initiating sleep but are not as effective as benzodiazepines for improving sleep quality or efficiency. Furthermore, their prolonged use produces adverse effects similar to those observed with benzodiazepines. Inasmuch as insomnia may be associated with decreased nocturnal melatonin, administration of melatonin is a strategy that has been increasingly used for treating insomnia. Melatonin can be effective for improving sleep quality without the adverse effects associated with hypnotic-sedatives. Ramelteon, a synthetic analog of melatonin which has a longer half life and a stronger affinity for MT1 and MT2 melatonergic receptors, has been reportedly effective for initiating and improving sleep in both adult and elderly insomniacs without showing hangover, dependence, or cognitive impairment. Insomnia is also a major complaint among patients suffering from depressive disorders and is often aggravated by conventional antidepressants especially the specific serotonin reuptake inhibitors. The novel antidepressant agomelatine, a dual action agent with affinity for melatonin MT1 and MT2 receptors and 5-HT2c antagonistic properties, constitutes a new approach to the treatment of major depressive disorders. Agomelatine ameliorates the symptoms of depression and improves the quality and efficiency of sleep. Taken together, the evidence indicates that MT1/MT2 receptor agonists like ramelteon or agomelatine may be valuable pharmacological tools for insomnia and for depression-associated insomnia.

Neuroendocrine-immune interactions in healthy aging

AIM

The nervous, endocrine and immune systems are connected by shared neurotransmitters, hormones and cytokines. The function of these systems shows patterns of circadian rhythmicity and a number of age-related changes in the 24-h hormonal and non-hormonal rhythms have been found in older human beings. The aim of this study was to evaluate integration among the nervous, endocrine and immune systems in the elderly.

METHODS

Cortisol and melatonin serum levels were measured and lymphocyte subpopulation analyses were performed on blood samples collected every 4 h for 24 h from 15 healthy young-middle-aged subjects (range 36-55 years, mean age±standard error [SE] 44.08±1.76) and 15 healthy old-aged subjects (range 67-79 years, mean age±SE 68.52±1.27).

RESULTS

There was a statistically significant difference between the groups in the observed values of CD20 (total B cells higher in young-middle-aged subjects, P=0.02), CD25 (activated T cells with expression of the α-chain of interleukin-2 receptor, higher in elderly subjects, P=0.04) and DR+ T cells (activated T cells higher in elderly subjects, P=0.01). There were different correlations among lymphocyte subpopulations and hormone serum levels in young and middle-aged subjects in compared to old-aged subjects. In the group of young-middle-aged subjects, a clear circadian rhythm was validated for the time-qualified changes of all the factors studied. In the group of elderly subjects, a clear circadian rhythm was validated for the nyctohemeral changes of CD3 (with a phase delay of 3 h), CD8, CD4/CD8 ratio, CD16, CD25 (in opposite phase), cortisol (with a phase delay of 1 h) and melatonin.

CONCLUSION

The results of the current study show that aging is associated with enhanced responsiveness of the T-cell compartment, impairment of B-cell compartment and alterations in temporal architecture and correlations of neuroendocrine-immune parameters.

The effect of melatonin, magnesium, and zinc on primary insomnia in long-term care facility residents in Italy: a double-blind, placebo-controlled clinical trial

OBJECTIVES

To determine whether nightly administration of melatonin, magnesium, and zinc improves primary insomnia in long-term care facility residents.

DESIGN

Double-blind, placebo-controlled clinical trial.

SETTING

One long-term care facility in Pavia, Italy.

PARTICIPANTS

Forty-three participants with primary insomnia (22 in the supplemented group, 21 in the placebo group) aged 78.3 ± 3.9.

INTERVENTION

Participants took a food supplement (5 mg melatonin, 225 mg magnesium, and 11.25 mg zinc, mixed with 100 g of pear pulp) or placebo (100 g pear pulp) every day for 8 weeks, 1 hour before bedtime.

MEASUREMENTS

The primary goal was to evaluate sleep quality using the Pittsburgh Sleep Quality Index. The Epworth Sleepiness Scale, the Leeds Sleep Evaluation Questionnaire (LSEQ), the Short Insomnia Questionnaire (SDQ), and a validated quality-of-life instrument (Medical Outcomes Study 36-item Short Form Survey (SF-36)) were administered as secondary end points. Total sleep time was evaluated using a wearable armband-shaped sensor. All measures were performed at baseline and after 60 days.

RESULTS

The food supplement resulted in considerably better overall PSQI scores than placebo (difference between groups in change from baseline PSQI score=6.8; 95% confidence interval=5.4-8.3, P<.001). Moreover, the significant improvements in all four domains of the LSEQ (ease of getting to sleep, P<.001; quality of sleep, P<.001; hangover on awakening from sleep, P=.005; alertness and behavioral integrity the following morning, P=.001), in SDQ score (P<.001), in total sleep time (P<.001), and in SF-36 physical score (P=.006) suggest that treatment had a beneficial effect on the restorative value of sleep.

CONCLUSION

The administration of nightly melatonin, magnesium, and zinc appears to improve the quality of sleep and the quality of life in long-term care facility residents with primary insomnia.

Relationship between circadian salivary melatonin levels and sleep-wake behavior in infants

BACKGROUND

There have been calls for more aggressive intervention for infants with failure in development of a sleep-wake rhythm. If development of the 'biological clock' in infants can be assessed by measuring melatonin, this may provide a useful indicator of the sleep-wake rhythm development. Thus, we investigated relationship between circadian salivary melatonin concentrations and sleep-wake behavioral parameters in infants.

METHODS

Sixty-seven mothers who had infants aged 3-15 months were requested to record sleep-wake behavior of their baby for 2 days, and to collect their baby's saliva four times daily in the morning (06:00-09:00 h), noon (11:00-13:00 h), evening (16:00-18:00 h), and night (19:00-22:00 h) for measurement of melatonin concentrations by ELISA.

RESULTS

The mean melatonin concentrations of the saliva were: morning 40 ± 4 pg/mL, noon 14 ± 3 pg/mL, evening 15 ± 3 pg/mL, and night 23 ± 4 pg/mL. The melatonin concentrations, at each measurement point, were highest in infants aged 3-5 months, and decreased as age increased. Morning melatonin concentrations showed a negative correlation with nocturnal sleep duration (P<0.05). Increased morning concentrations were related to early waking time (P<0.05). In infants with open air baths on most days, evening and night melatonin concentrations were significantly lower (P<0.05).

CONCLUSION

Salivary melatonin concentrations in infants between 06:00 and 22:00 decreased by age, and elevation of morning values may indicate an immature sleep-wake rhythm. Frequent open air baths may contribute to decreased melatonin levels.

Nightly treatment of primary insomnia with prolonged release melatonin for 6 months: a randomized placebo controlled trial on age and endogenous melatonin as predictors of efficacy and safety

BACKGROUND

Melatonin is extensively used in the USA in a non-regulated manner for sleep disorders. Prolonged release melatonin (PRM) is licensed in Europe and other countries for the short term treatment of primary insomnia in patients aged 55 years and over. However, a clear definition of the target patient population and well-controlled studies of long-term efficacy and safety are lacking. It is known that melatonin production declines with age. Some young insomnia patients also may have low melatonin levels. The study investigated whether older age or low melatonin excretion is a better predictor of response to PRM, whether the efficacy observed in short-term studies is sustained during continued treatment and the long term safety of such treatment.

METHODS

Adult outpatients (791, aged 18-80 years) with primary insomnia, were treated with placebo (2 weeks) and then randomized, double-blind to 3 weeks with PRM or placebo nightly. PRM patients continued whereas placebo completers were re-randomized 1:1 to PRM or placebo for 26 weeks with 2 weeks of single-blind placebo run-out. Main outcome measures were sleep latency derived from a sleep diary, Pittsburgh Sleep Quality Index (PSQI), Quality of Life (World Health Organzaton-5) Clinical Global Impression of Improvement (CGI-I) and adverse effects and vital signs recorded at each visit.

RESULTS

On the primary efficacy variable, sleep latency, the effects of PRM (3 weeks) in patients with low endogenous melatonin (6-sulphatoxymelatonin [6-SMT] <or=8 microg/night) regardless of age did not differ from the placebo, whereas PRM significantly reduced sleep latency compared to the placebo in elderly patients regardless of melatonin levels (-19.1 versus -1.7 min; P = 0.002). The effects on sleep latency and additional sleep and daytime parameters that improved with PRM were maintained or enhanced over the 6-month period with no signs of tolerance. Most adverse events were mild in severity with no clinically relevant differences between PRM and placebo for any safety outcome.

CONCLUSIONS

The results demonstrate short- and long-term efficacy and safety of PRM in elderly insomnia patients. Low melatonin production regardless of age is not useful in predicting responses to melatonin therapy in insomnia. The age cut-off for response warrants further investigation.

Non-pharmacologic management of sleep disturbance in Alzheimer's disease

Sleep and wake in Alzheimer's disease (AD) are often fragmented as manifested by bouts of wakefulness at night and napping during the day. Management of sleep disturbances in AD is important because of their negative impact on both patients and caregivers. Pharmacological treatments, mainly sedative-hypnotics and antipsychotics, are often used but can be associated with significant adverse effects. Non-pharmacological treatments represent a beneficial alternative approach to the management of sleep disturbances in AD since they are associated with fewer adverse effects and their efficacy can be sustained after treatment has been completed. The aim of this article is to review non-pharmacological treatments, such as sleep hygiene, sleep restriction therapy (SRT), cognitive behavioral therapy (CBT), light therapy, and continuous positive airway pressure (CPAP), for the management of sleep/wake disturbances in AD.

Vitex agnus-castus (Chaste-Tree/Berry) in the treatment of menopause-related complaints

BACKGROUND

The origin of the current practice of administering Vitex agnus-castus in menopause-related complaints is uncertain, but appears to be relatively recent. Here we review the evidence for this application of Vitex based on evidence from pharmacological studies and clinical research.

METHODS

The mechanisms of potential relevance in the context of menopause are explored with reference to the current understanding of the endocrinology and neuroendocrinology of menopause and associated symptoms.

CONCLUSIONS

We conclude that, while evidence from rigorous randomized controlled trials is lacking for the individual herb in this context, emerging pharmacological evidence supports a role for V. agnus-castus in the alleviation of menopausal symptoms and suggests that further investigation may be appropriate.

The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomnia

Objectives of this study were to investigate the effects of prolonged-release melatonin 2 mg (PRM) on sleep and subsequent daytime psychomotor performance in patients aged > or =55 years with primary insomnia, as defined by fourth revision of the Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association. Patients (N = 40) were treated nightly single-blind with placebo (2 weeks), randomized double-blind to PRM or placebo (3 weeks) followed by withdrawal period (3 weeks). Sleep was assessed by polysomnography, all-night sleep electroencephalography spectral analysis and questionnaires. Psychomotor performance was assessed by the Leeds Psychomotor Test battery. By the end of the double-blind treatment, the PRM group had significantly shorter sleep onset latency (9 min; P = 0.02) compared with the placebo group and scored significantly better in the Critical Flicker Fusion Test (P = 0.008) without negatively affecting sleep structure and architecture. Half of the patients reported substantial improvement in sleep quality at home with PRM compared with 15% with placebo (P = 0.018). No rebound effects were observed during withdrawal. In conclusion, nightly treatment with PRM effectively induced sleep and improved perceived quality of sleep in patients with primary insomnia aged > or =55 years. Daytime psychomotor performance was not impaired and was consistently better with PRM compared with placebo. PRM was well tolerated with no evidence of rebound effects.

Hyperarousal and insomnia: state of the science

In the past few years it has become increasingly clear that insomnia is a chronic disease that interacts with many other medical conditions. As our ability to examine complex physiological activity during sleep has increased, additional evidence continues to suggest that insomnia is associated with inappropriate physiological arousal. It is now known that patients with primary insomnia have increased high-frequency EEG activation, abnormal hormone secretion, increased whole body and brain metabolic activation, and elevated heart rate and sympathetic nervous system activation during sleep. This activation can be measured throughout the day and night and is chronic. Other research suggests that insomnia, probably based upon the associated chronic physiologic arousal, is associated with increased risk for medical disorders such as depression, hypertension, or cardiac disease. An animal model that has used odor stress to produce poor sleep in rats has identified specific activated brain sites similar to those found in human brain metabolic studies to suggest that insomnia is a state in which sleep and arousal systems are both simultaneously active. The animal studies have also shown that the inappropriate arousal can be blocked by lesions in the limbic and arousal systems. It is hoped that these findings can be extended to identify new compounds that improve insomnia by acting at these sites of abnormal brain activation.

Morning Melatonin Has Limited Benefit as a Soporific For Daytime Sleep After Night Work

Exogenous melatonin administration in humans is known to exert both chronobiotic (phase shifting) and soporific effects. In a previous study in our lab, young, healthy, subjects worked five consecutive simulated night shifts (23:00 to 07:00 h) and slept during the day (08:30 to 15:30 h). Large phase delays of various magnitudes were produced by the study interventions, which included bright light exposure during the night shifts, as assessed by the dim light melatonin onset (DLMO) before (baseline) and after (final) the five night shifts. Subjects also ingested either 1.8 mg sustained-release melatonin or placebo before daytime sleep. Although melatonin at this time should delay the circadian clock, this previous study found that it did not increase the magnitude of phase delays. To determine whether melatonin had a soporific effect, we controlled the various magnitudes of phase delay produced by the other study interventions. Melatonin (n=18) and placebo (n=18) groups were formed by matching a melatonin participant with a placebo participant that had a similar baseline and final DLMO (+/-1 h). Sleep log measurements of total sleep time (TST) and actigraphic measurements of sleep latency, TST, and three movement indices for the two groups were examined. Although melatonin was associated with small improvements in sleep quality and quantity, the differences were not statistically significant by analysis of variance. However, binomial analysis indicated that melatonin participants were more likely to sleep better than their placebo counterparts on some days with some measures. It was concluded that, the soporific effect of melatonin is small when administered prior to 7 h daytime sleep periods following night shift work.

Melatonin and melatonergic drugs on sleep: possible mechanisms of action

Pineal melatonin is synthesized and secreted in close association with the light/dark cycle. The temporal relationship between the nocturnal rise in melatonin secretion and the "opening of the sleep gate" (i.e., the increase in sleep propensity at the beginning of the night), coupled with the sleep-promoting effects of exogenous melatonin, suggest that melatonin is involved in the regulation of sleep. The sleep-promoting and sleep/wake rhythm regulating effects of melatonin are attributed to its action on MT(1) and MT(2) melatonin receptors present in the suprachiasmatic nucleus (SCN) of the hypothalamus. Animal experiments carried out in rats, cats, and monkeys have revealed that melatonin has the ability to reduce sleep onset time and increase sleep duration. However, clinical studies reveal inconsistent findings, with some of them reporting beneficial effects of melatonin on sleep, whereas in others only marginal effects are documented. Recently a prolonged-release 2-mg melatonin preparation (Circadin(TM)) was approved by the European Medicines Agency as a monotherapy for the short-term treatment of primary insomnia in patients who are aged 55 or above. Several melatonin derivatives have been shown to increase nonrapid eye movement (NREM) in rats and are of potential pharmacological importance. So far only one of these melatonin derivatives, ramelteon, has received approval from the U.S. Food and Drug Administration to be used as a sleep promoter. Ramelteon is a novel MT(1) and MT(2) melatonergic agonist that has specific effects on melatonin receptors in the SCN and is effective in promoting sleep in experimental animals such as cats and monkeys. In clinical trials, ramelteon reduced sleep onset latency and promoted sleep in patients with chronic insomnia, including an older adult population. Both melatonin and ramelteon promote sleep by regulating the sleep/wake rhythm through their actions on melatonin receptors in the SCN, a unique mechanism of action not shared by any other hypnotics. Moreover, unlike benzodiazepines, ramelteon causes neither withdrawal effects nor dependence. Agomelatine, another novel melatonergic antidepressant in its final phase of approval for clinical use, has been shown to improve sleep in depressed patients and to have an antidepressant efficacy that is partially attributed to its effects on sleep-regulating mechanisms.

Sleep disorders and their impacts on healthy, dependent, and frail older adults

BACKGROUND

Sleep disorders differ widely in the heterogeneous older adult population. Older adults can be classified into three groups based upon their overall level of disability: healthy, dependent, and frail. Frailty is an emerging concept that denotes older persons at increased risk for poor outcomes.

OBJECTIVE

The aim of this consensus review is to describe the sleep disorders observed in healthy and dependent older adults and to discuss the potential sleep disorders associated with frailty as well as their potential consequences on this weakened population.

METHODS

A review task force was created including neurologists, geriatricians, sleep specialists and geriatric psychiatrists to discuss age related sleep disorders depending on the three categories of older adults. All published studies on sleep in older adults on Ovid Medline were reviewed and 106 articles were selected for the purpose of this consensus.

RESULTS

Many healthy older adults have complains about their sleep such as waking not rested and too early, trouble falling asleep, daytime napping, and multiple nocturnal awakenings. Sleep architecture is modified by age with an increased percentage of time spent in stage one and a decreased percentage spent in stages three and four. Insomnia is frequent and its mechanisms include painful medical conditions, psychological distress, loss of physical activity and iatrogenic influences. Treatments are also involved in older adults' somnolence. The prevalence of primary sleep disorders such as restless legs syndrome, periodic limb movements and sleep disordered breathing increases with age. Potential outcomes relevant to these sleep disorders in old age include mortality, cardiovascular and neurobehavioral co-morbidities. Sleep in dependent older adults such as patients with Alzheimer Disease (AD) is disturbed. The sleep patterns observed in these patients are often similar to those observed in non-demented elderly but alterations are more severe. Nocturnal sleep disruption and daytime sleepiness are the main problems. They are the results of Sleep/wake circadian rhythm disorders, environmental, psychological and iatrogenic factors. They are worsened by other sleep disorders such as sleep disordered breathing. Sleep in frail older adults per se has not yet been formally studied but four axes of investigation should be considered: i) sleep architecture abnormalities, ii) insomnia iii) restless legs syndrome (RLS), iv) sleep disordered breathing.

CONCLUSION

Our knowledge in the field of sleep disorders in older adults has increased in recent years, yet some groups within this heterogeneous population, such as frail older adults, remain to be more thoroughly studied and characterized.

Effects of prolonged-release melatonin, zolpidem, and their combination on psychomotor functions, memory recall, and driving skills in healthy middle aged and elderly volunteers

BACKGROUND

Melatonin is an important regulator of the sleep-wake cycle. A prolonged-release formulation of melatonin (PR-M) that essentially mimics the profile of the endogenous production of the hormone is effective in the treatment of insomnia in patients aged 55 years and older. Because hypnotics result in impairments of various cognitive skills, it is important to examine the cognitive effects associated with the use of PR-M.

OBJECTIVES AND METHODS

The effects of therapeutic oral doses of PR-M (2 mg), zolpidem (10 mg) and their combination administered at bedtime on cognitive functions in healthy subjects aged 55 years and older (12 males + 4 females, age 59.4 +/- 3.2 years) were assessed in a randomized, double-blind, placebo-controlled, and four-way crossover study. Psychomotor functions, memory recall, and driving skills were assessed at 1 and 4 h following administration and the next morning.

RESULTS

Compared to placebo, PR-M alone did not impaired performances on any cognitive tasks. Zolpidem significantly impaired psychomotor and driving performance 1 h and 4 h post-dosing, and early memory recall; these impairment were exacerbated with PR-M co-administration. No effects on next morning psychomotor or driving performance were observed except that the decline in memory recall after zolpidem was more pronounced in the next day. No pharmacokinetic interactions were found.

CONCLUSIONS

This study extends previous researches showing impairment of cognitive functions by zolpidem within 5 h post-administration. Further, PR-M use was not found associated with impairment of psychomotor functions, memory recall, and driving skills, and point to a pharmacodynamic interaction between melatonin and GABA-A modulators.

Efficacy and hypnotic effects of melatonin in shift-work nurses: double-blind, placebo-controlled crossover trial

Background

Night work is associated with disturbed sleep and wakefulness, particularly in relation to the night shift. Circadian rhythm sleep disorders are characterized by complaints of insomnia and excessive daytime sleepiness that are primarily due to alterations in the internal circadian timing system or a misalignment between the timing of sleep and the 24-h social and physical environment.

Methods

We evaluated the effect of oral intake of 5 mg melatonin taken 30 minutes before night time sleep on insomnia parameters as well as subjective sleep onset latency, number of awakenings, and duration of sleep. A double-blind, randomized, placebo-controlled crossover study with periods of 1 night and washouts of 4 days comparing melatonin with placebo tablets was conducted. We tried to improve night-time sleep during recovery from night work. Participants were 86 shift-worker nurses aged 24 to 46 years. Each participant completed a questionnaire immediately after awakening.

Results

Sleep onset latency was significantly reduced while subjects were taking melatonin as compared with both placebo and baseline. There was no evidence that melatonin altered total sleep time (as compared with baseline total sleep time). No adverse effects of melatonin were noted during the treatment period.

Conclusion

Melatonin may be an effective treatment for shift workers with difficulty falling asleep.

The roles of melatonin and light in the pathophysiology and treatment of circadian rhythm sleep disorders

Normal circadian rhythms are synchronized to a regular 24 h environmental light-dark cycle, and the suprachiasmatic nucleus and the hormone melatonin have important roles in this process. Desynchronization of circadian rhythms, as occurs in chronobiological disorders, can produce severe disturbances in sleep patterns. According to the International Classification of Sleep Disorders, circadian rhythm sleep disorders (CRSDs) include delayed sleep phase syndrome, advanced sleep phase syndrome, non-24 h sleep-wake disorder, jet lag and shift-work sleep disorder. Disturbances in the circadian phase position of plasma melatonin levels have been documented in all of these disorders. There is compelling evidence to implicate endogenous melatonin as an important mediator in CRSD pathophysiology, although further research involving large numbers of patients will be required to clarify whether the disruption of melatonin secretion is a causal factor in CRSDs. In this Review, we focus on the use of exogenous melatonin and light therapy to treat the disturbed sleep-wake rhythms seen in CRSDs.

Live to the rhythm, slave to the rhythm

Circadian rhythms in health and disease have most often been described in terms of their phases and amplitudes, and how these respond to a single exposure to stimuli denoted as zeitgebers. The present paper argues that it is also important to consider the 24-h regularity in the repeated occurrence of the zeitgebers. The effect of the regularity of stimulation by light, melatonin, physical activity, body temperature, corticosteroids and feeding on synchronization within and between the central circadian clock and peripheral oscillators is discussed. In contrast to the phase shifts that can be recorded acutely after a single zeitgeber pulse, the effects of irregularly versus regularly timed zeitgeber can be studied only in long-term protocols and may develop slowly, which is a possible reason why they have received relatively little attention. Several observations indicate a reciprocal relation between the robustness of the endogenous circadian timing system and its dependency on regularly timed zeitgebers. Especially at old age and in disease, proper functioning of the circadian timing system may become more dependent on regularly timed exposure to zeitgeber stimuli. in such conditions, regularly timed exposure to zeitgeber appears to be highly important for health. After a concise introduction on inputs to the central and peripheral oscillators of the circadian timing system, the paper discusses the responses of the circadian timing system and health to (1) a chronic lack of zeitgeber stimuli; (2) fragmented or quasi-ultradian stimuli and (3) repeated phase shifts in stimuli. Subsequently, the specific relevance to aging is discussed, followed by an overview of the effects of experimentally imposed regularly timed stimuli. Finally, a possible mechanism for the gradually evolving effects of repeated regularly timed stimuli on the circadian timing system is proposed.

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

The circadian rhythm of pineal melatonin secretion, which is controlled by the suprachiasmatic nucleus (SCN), is reflective of mechanisms that are involved in the control of the sleep/wake cycle. Melatonin can influence sleep-promoting and sleep/wake rhythm-regulating actions through the specific activation of MT(1) (melatonin 1a) and MT(2) (melatonin 1b) receptors, the two major melatonin receptor subtypes found in mammals. Both receptors are highly concentrated in the SCN. In diurnal animals, exogenous melatonin induces sleep over a wide range of doses. In healthy humans, melatonin also induces sleep, although its maximum hypnotic effectiveness, as shown by studies of the timing of dose administration, is influenced by the circadian phase. In both young and elderly individuals with primary insomnia, nocturnal plasma melatonin levels tend to be lower than those in healthy controls. There are data indicating that, in affected individuals, melatonin therapy may be beneficial for ameliorating insomnia symptoms. Melatonin has been successfully used to treat insomnia in children with attention-deficit hyperactivity disorder or autism, as well as in other neurodevelopmental disorders in which sleep disturbance is commonly reported. In circadian rhythm sleep disorders, such as delayed sleep-phase syndrome, melatonin can significantly advance the phase of the sleep/wake rhythm. Similarly, among shift workers or individuals experiencing jet lag, melatonin is beneficial for promoting adjustment to work schedules and improving sleep quality. The hypnotic and rhythm-regulating properties of melatonin and its agonists (ramelteon, agomelatine) make them an important addition to the armamentarium of drugs for treating primary and secondary insomnia and circadian rhythm sleep disorders.

Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effects

Melatonin, secreted nocturnally by the pineal gland, is an endogenous sleep regulator. Impaired melatonin production and complaints on poor quality of sleep are common among the elderly. Non-restorative sleep (perceived poor quality of sleep) and subsequently poor daytime functioning are increasingly recognized as a leading syndrome in the diagnostic and therapeutic process of insomnia complaints. The effects of 3-weeks prolonged-release melatonin 2 mg (PR-melatonin) versus placebo treatment were assessed in a multi-center randomized placebo-controlled study in 170 primary insomnia outpatients aged > or =55 years. Improvements in quality of sleep (QOS) the night before and morning alertness (BFW) were assessed using the Leeds Sleep Evaluation Questionnaire and changes in sleep quality (QON) reported on five categorical unit scales. Rebound insomnia and withdrawal effects following discontinuation were also evaluated. PR-melatonin significantly improved QOS (-22.5 versus -16.5 mm, P = 0.047), QON (0.89 versus 0.46 units; P = 0.003) and BFW (-15.7 versus -6.8 mm; P = 0.002) compared with placebo. The improvements in QOS and BFW were strongly correlated (Rval = 0.77, P < 0.001) suggesting a beneficial treatment effect on the restorative value of sleep. These results were confirmed in a subgroup of patients with a greater symptom severity. There was no evidence of rebound insomnia or withdrawal effects following treatment discontinuation. The incidence of adverse events was low and most side-effects were judged to be of minor severity. PR-melatonin is the first drug shown to significantly improve quality of sleep and morning alertness in primary insomnia patients aged 55 years and older-suggesting more restorative sleep, and without withdrawal symptoms upon discontinuation.

Pharmacotherapy of insomnia

Insomnia is the most common sleep disorder in the industrialized world. A variety of precipitating events have been identified, but when it becomes a persistent problem, maladaptive patterns become established, thereby, perpetuating the sleep disturbance. Individuals with insomnia have impaired next-day functioning, which impacts their quality of life and places them at increased risk of motor vehicle accidents. Insomnia is commonly associated with chronic medical conditions, as well as an increased incidence of mental disorders. Despite considerable scientific advances in both the understanding and treatment, insomnia continues to be inadequately identified and treated, with < 15% of those with severe insomnia receiving appropriate treatment. The mainstay of treatment for insomnia is cognitive-behavioral therapy, along with judicious use of hypnotic agents.

Prolonged-release melatonin for the treatment of insomnia: targeting quality of sleep and morning alertness

Prolonged-release (PR) melatonin (Circadin®, Neurim Pharmaceuticals, Tel-Aviv, Israel) is a nonbenzodiazepine licensed to treat primary insomnia in patients aged 55 years and older. It exerts its effects by mimicking endogenous melatonin, a hormone which regulates sleep. PR-melatonin has been shown to be effective in improving quality of sleep and morning alertness. An oral dose of 2 mg once-daily for 3 weeks has generally been well tolerated, and does not cause ‘hangover’ effects or impair memory and psychomotor skills.