Melatonin replacement therapy of elderly insomniacs

Prolonged release melatonin in the treatment of primary insomnia: evaluation of the age cut-off for short- and long-term response

OBJECTIVES

The authors recently reported on efficacy and safety of prolonged-release melatonin formulation (PRM; Circadin 2  mg) in elderly insomnia patients. The age cut-off for response to PRM and the long-term maintenance of efficacy and safety were further evaluated by looking at the total cohort (age 18-80 years) from that study and subsets of patients aged 18-54 and 55-80 years (for whom the drug is currently indicated).

DESIGN

Randomised, double-blind, placebo controlled trial.

SETTING

Multicentre, outpatients, primary care setting.

METHODS

A total of 930 males and females aged 18-80 years with primary insomnia who reported mean nightly sleep latency (SL) >20  min were enrolled and 791 entered the active phase of the study. The study comprised a 2-week, single-blind placebo run-in period followed by 3 week's double-blind treatment with PRM or placebo, one tablet per day at 2 hours before bedtime. PRM patients continued whereas placebo completers were re-randomised 1:1 to PRM or placebo for 26 weeks followed by 2-weeks run-out on placebo.

MAIN OUTCOME MEASURES

SL and other sleep variables derived from sleep diary, Pittsburgh Sleep Quality Index (PSQI), Quality of life (WHO-5), Clinical Global Impression of Improvement (CGI-I) and adverse effects, recorded each visit, withdrawal and rebound effects during run-out.

RESULTS

In all, 746 patients completed the 3-week and 555 (421 PRM, 134 placebo) completed the 6-month period. The principal reason for drop-out was patient decision. At 3 weeks, significant differences in SL (diary, primary variable) in favour of PRM vs. placebo treatment were found for the 55-80-year group (-15.4 vs. -5.5  min, p = 0.014) but not the 18-80-year cut-off which included younger patients. Other variables (SL-PSQI, PSQI, WHO-5, CGI-I scores) improved significantly with PRM in the 18-80-year population, more so than in the 55-80-year age group. Improvements were maintained or enhanced over the 6-month period with no signs of tolerance. No withdrawal symptoms or rebound insomnia were detected. Most adverse events were mild with no significant differences between PRM and placebo groups in any safety outcome.

CONCLUSIONS

The results demonstrate short- and long-term efficacy of PRM in insomnia patients aged 18-80 years, particularly those aged 55 and over. PRM was well-tolerated over the entire 6-month period with no rebound or withdrawal symptoms following discontinuation. Study Registry No: ClinicalTrials.gov ID: NCT00397189.

Effectiveness of melatonin treatment on circadian rhythm disturbances in dementia. Are there implications for delirium? A systematic review

OBJECTIVE

Circadian rhythm disturbances, like sundowning, are seen in dementia. Because the circadian rhythm is regulated by the biological clock, melatonin might be effective in the treatment of these disturbances. We systematically studied the effect of melatonin treatment in patients with dementia. In addition, we elaborate on the possible effects one might expect of melatonin treatment in patients with delirium, since dementia and delirium are strongly related. Moreover, some evidence exists that sundowning in patients with dementia and the alterations in the sleep/wake cycle, seen in patients with delirium both originate from circadian rhythm disturbances.

DESIGN

A systematic search of the literature, published between 1985 and April 2009, was performed using PubMed and other databases. All papers on melatonin treatment in dementia were retrieved. Effects of melatonin on circadian rhythm disturbances were scored by means of scoring sundowning/agitated behaviour, sleep quality and daytime functioning.

RESULTS

Nine papers, including four randomised controlled trials (RCTs) (n = 243), and five case series (n = 87) were reviewed. Two of the RCTs found a significant improvement on sundowning/agitated behaviour. All five case series found an improvement. The results on sleep quality and daytime functioning were inconclusive.

CONCLUSION

Sundowning/agitated behaviour improves with melatonin treatment in patients with dementia. There are several arguments that sundowning in patients with dementia and the alterations in the sleep/wake cycle in patients with delirium have a common background, namely a disturbance of the circadian rhythm. This suggests that melatonin treatment could also have the same positive effects in patients with delirium.

International Union of Basic and Clinical Pharmacology. LXXV. Nomenclature, classification, and pharmacology of G protein-coupled melatonin receptors

The hormone melatonin (5-methoxy-N-acetyltryptamine) is synthesized primarily in the pineal gland and retina, and in several peripheral tissues and organs. In the circulation, the concentration of melatonin follows a circadian rhythm, with high levels at night providing timing cues to target tissues endowed with melatonin receptors. Melatonin receptors receive and translate melatonin's message to influence daily and seasonal rhythms of physiology and behavior. The melatonin message is translated through activation of two G protein-coupled receptors, MT(1) and MT(2), that are potential therapeutic targets in disorders ranging from insomnia and circadian sleep disorders to depression, cardiovascular diseases, and cancer. This review summarizes the steps taken since melatonin's discovery by Aaron Lerner in 1958 to functionally characterize, clone, and localize receptors in mammalian tissues. The pharmacological and molecular properties of the receptors are described as well as current efforts to discover and develop ligands for treatment of a number of illnesses, including sleep disorders, depression, and cancer.

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.

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.

Sleep disturbance and melatonin levels following traumatic brain injury

OBJECTIVES

Sleep disturbances commonly follow traumatic brain injury (TBI) and contribute to ongoing disability. However, there are no conclusive findings regarding specific changes to sleep quality and sleep architecture measured using polysomnography. Possible causes of the sleep disturbances include disruption of circadian regulation of sleep-wakefulness, psychological distress, and a neuronal response to injury. We investigated sleep-wake disturbances and their underlying mechanisms in a TBI patient sample.

METHODS

This was an observational study comparing 23 patients with TBI (429.7 +/- 287.6 days post injury) and 23 age- and gender-matched healthy volunteers on polysomnographic sleep measures, salivary dim light melatonin onset (DLMO) time, and self-reported sleep quality, anxiety, and depression.

RESULTS

Patients with TBI reported higher anxiety and depressive symptoms and sleep disturbance than controls. Patients with TBI showed decreased sleep efficiency (SE) and increased wake after sleep onset (WASO). Although no significant group differences were found in sleep architecture, when anxiety and depression scores were controlled, patients with TBI showed higher amount of slow wave sleep. No differences in self-reported sleep timing or salivary DLMO time were found. However, patients with TBI showed significantly lower levels of evening melatonin production. Melatonin level was significantly correlated with REM sleep but not SE or WASO.

CONCLUSIONS

Reduced evening melatonin production may indicate disruption to circadian regulation of melatonin synthesis. The results suggest that there are at least 2 factors contributing to sleep disturbances in patients with traumatic brain injury. We propose that elevated depression is associated with reduced sleep quality, and increased slow wave sleep is attributed to the effects of mechanical brain damage.

Actigraphic assessment of daily sleep-activity pattern abnormalities reflects self-assessed depression and anxiety in outpatients with advanced non-small cell lung cancer

OBJECTIVES

We measured subjectively evaluated depression and anxiety, and objectively measured daily sleep-activity patterns in inpatients and outpatients with advanced non-small cell lung cancer (NSCLC) and determined whether cancer-associated depression and anxiety are accompanied by characteristic circadian rhythm abnormalities.

METHODS

Equal numbers of inpatients (n=42) and outpatients (n=42) with advanced NSCLC were studied. Baseline depression and anxiety, assessed by the Hospital Anxiety and Depression Scale (HADS), and actigraphy were recorded before chemotherapy initiation. The effects of the presence and severity of chronic obstructive pulmonary disease (COPD) on depression, anxiety, and actigraphy were assessed only among the 42 outpatients.

RESULTS

Anxiety occurred in 40% and depression in 25% of these lung cancer patients, equally among inpatients and outpatients. All patients suffer extremely disturbed daily sleep-activity cycles but each patient also maintains some degree of circadian organization. Outpatients maintain more robust daily activity patterns and longer, more consolidated nighttime sleep compared with inpatients. The more disrupted the daily sleep-activity rhythm, the worse the depression and/or anxiety scores for outpatients. These relationships are obscured among inpatients. COPD has no independent measurable effects on the daily organization of sleep-activity, depression, or anxiety.

CONCLUSIONS

Lung cancer patients whose diurnal activity is disturbed by prolonged and frequent sedentary episodes and whose sleep is disturbed by frequent and prolonged waking are most anxious and depressed. These findings and relationships are masked by hospitalization. Since diurnal exercise improves both sleep and mood, it is reasonable to test whether enhancing daytime activity and nighttime sleep can diminish cancer-associated depression.

Physiology and pharmacology of melatonin in relation to biological rhythms

Melatonin is an evolutionarily conserved molecule that serves a time-keeping function in various species. In vertebrates, melatonin is produced predominantly by the pineal gland with a marked circadian rhythm that is governed by the central circadian pacemaker (biological clock) in the suprachiasmatic nuclei of the hypothalamus. High levels of melatonin are normally found at night, and low levels are seen during daylight hours. As a consequence, melatonin has been called the "darkness hormone". This review surveys the current state of knowledge regarding the regulation of melatonin synthesis, receptor expression, and function. In particular, it addresses the physiological, pathological, and therapeutic aspects of melatonin in humans, with an emphasis on biological rhythms.

Actigraphy in agitated patients with dementia. Monitoring treatment outcomes

Especially in pharmacotherapeutic research, a variety of methods to monitor behavioural and psychological symptoms of dementia (BPSD) are currently being discussed. To date, the most frequently used of these are clinical scales, which, however, are subjective and highly dependent on personnel resources. In our study, we tested the usefulness of actigraphy as a more direct and objective way to measure day-night rhythm disturbances and agitated behaviour. After a baseline assessment, 24 patients with probable dementia of the Alzheimer type (NINCDS-ADRDA) and agitated behaviour received either 3 mg melatonin (n=7), 2.5 mg dronabinol (n=7), or placebo (n=10) for two weeks. In addition, 10 young and 10 elderly healthy subjects were examined as a control group. Motor activity levels were assessed using an actigraph worn continuously on the wrist of the non-dominant hand. At the beginning and the end of the study, patients' Neuropsychiatric Inventory (NPI) scores were also assessed. In the verum group, actigraphic nocturnal activity (P=0.001), NPI total score (P=0.043), and NPI agitation subscale score (P=0.032) showed significant reductions compared to baseline. The treatment-baseline ratio of nocturnal activity (P=0.021) and treatment-baseline difference of the nocturnal portion of 24 h activity (P=0.012) were reduced. Patients' baseline activity levels were similar to those seen in healthy elderly subjects. Younger healthy subjects exhibited higher motor activity even at night. There was no correlation between actigraphy and NPI. Both actigraphic measures and the gold standard clinical scale were able to distinguish between the verum and placebo groups. However, because they did not correlate with each other, they clearly represent different aspects of BPSD, each of which reacts differently to therapy. As a result, actigraphy may well come to play an important role in monitoring treatment success in BPSD.

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.

Ramelteon: a review of its therapeutic potential in sleep disorders

Ramelteon is a tricyclic synthetic analog of melatonin that acts specifically on MT(1) and MT(2) melatonin receptors. Ramelteon's half-life is longer than that of melatonin, being metabolized in the body to four main metabolites, M-I, M-II, M-III, and M-IV. M-II has an affinity to MT(1) and MT(2) of about one-tenth of the parent compound, but its concentration in the circulation exceeds that of ramelteon by more than an order of magnitude. Ramelteon is effective in decreasing latency to persistent sleep and increasing total sleep time in freely moving monkeys. A number of clinical studies have been undertaken to study the efficacy of ramelteon in subjects with chronic insomnia. In almost all of these studies, ramelteon, in various doses of 4, 8, or 16 mg most commonly, significantly reduced sleep latency and increased sleep duration. Its primary action in sleep promotion is not a generalized gamma-aminobutyric (GABA)-ergic central nervous system depression, but rather it acts as a melatonergic agonist in the suprachiasmatic nucleus (and at other central nervous system sites), from where downstream processes, including GABA-ergic effects, are controlled via the hypothalamic sleep switch. Unlike other commonly prescribed hypnotic drugs, ramelteon is not associated with next morning hangover effects or reductions in alertness, nor has it been shown to cause withdrawal symptoms. The adverse symptoms reported with ramelteon are mild. All long-term investigations that have been carried out support the conclusion that ramelteon is a well tolerated and effective drug for the treatment of insomnia.

Pharmacologic treatment of disturbed sleep in the elderly

Disturbed sleep is common in the elderly, who, as a group, take a disproportionately large number of hypnotic medications. Benzodiazepine hypnotics, as well as the newer benzodiazepine receptor agonists, are the primary treatments for these late-life sleep disorders and are effective and safe when used within recommended prescribing guidelines. The elderly also receive other psychiatric medications to induce sleep, although these are off-label uses not well supported by research literature. There is also no literature support for the use of over-the-counter sleep preparations, although both melatonin and a melatonin receptor agonist appear to be moderately effective and safe. Prescribing guidelines for the elderly continue to emphasize short-term, low-dose use, with short-half-life medications. Hypnotic drugs should be used in conjunction with nonmedication treatments, including appropriate sleep hygiene practice, and treatment of other medical or psychiatric causes of disturbed sleep.

Effect of melatonin administration on sleep, behavioral disorders and hypnotic drug discontinuation in the elderly: a randomized, double-blind, placebo-controlled study

BACKGROUND AND AIMS

The aim of the study was to evaluate the effect of melatonin administration on sleep and behavioral disorders in the elderly and the facilitation of the discontinuation of regular hypnotic drugs.

METHODS

This was a prospective, randomized, double-blind, placebo-controlled, crossover trial in a community-living population. Participants were 22 older adults (7 men, 15 women over 65) with a history of sleep disorder complaints. Fourteen of these subjects were receiving hypnotic drug therapy. Participants received 2 months of melatonin (5 mg/day) and 2 months of placebo. Sleep disorders were evaluated with the Northside Hospital Sleep Medicine Institute (NHSMI) test, discarding secondary insomnia and evaluating sleep quality. Behavioral disorders were evaluated with the Yesavage Geriatric Depression Scale (GDS) and Goldberg Anxiety Scale (GAS). Patients discontinuing hypnotic drugs were also recorded.

RESULTS

Melatonin treatment for two months significantly improved sleep quality scores measured by the NHSMI test (1.78+/-0.40) when compared with both basal (3.72+/-0.45; p=0.001) and placebo (3.44+/-0.56; p=0.025) groups. Depression measured by GDS and anxiety measured by GAS also improved significantly after melatonin administration (p=0.043 and p=0.009, respectively). Nine out of 14 subjects receiving hypnotic drugs were able to discontinue this treatment during melatonin but not placebo administration; one discontinued hypnotic drugs during both melatonin and placebo administration, and four were unable to discontinue hypnotic therapy.

CONCLUSIONS

The results of this study suggest that melatonin administration significantly improves sleep and behavioral disorders in the elderly and facilitates discontinuation of therapy with conventional hypnotic drugs.

New approaches in the management of insomnia: weighing the advantages of prolonged-release melatonin and synthetic melatoninergic agonists

Hypnotic effects of melatonin and melatoninergic drugs are mediated via MT(1) and MT(2) receptors, especially those in the circadian pacemaker, the suprachiasmatic nucleus, which acts on the hypothalamic sleep switch. Therefore, they differ fundamentally from GABAergic hypnotics. Melatoninergic agonists primarily favor sleep initiation and reset the circadian clock to phases allowing persistent sleep, as required in circadian rhythm sleep disorders. A major obstacle for the use of melatonin to support sleep maintenance in primary insomnia results from its short half-life in the circulation. Solutions to this problem have been sought by developing prolonged-release formulations of the natural hormone, or melatoninergic drugs of longer half-life, such as ramelteon, tasimelteon and agomelatine. With all these drugs, improvements of sleep are statistically demonstrable, but remain limited, especially in primary chronic insomnia, so that GABAergic drugs may be indicated. Melatoninergic agonists do not cause next-day hangover and withdrawal effects, or dependence. They do not induce behavioral changes, as sometimes observed with z-drugs. Despite otherwise good tolerability, the use of melatoninergic drugs in children, adolescents, and during pregnancy has been a matter of concern, and should be avoided in autoimmune diseases and Parkinsonism. Problems and limits of melatoninergic hypnotics are compared.

Pharmacology of ramelteon, a selective MT1/MT2 receptor agonist: a novel therapeutic drug for sleep disorders

An estimated one-third of the general population is affected by insomnia, and this number is increasing due to more stressful working conditions and the progressive aging of society. However, current treatment of insomnia with hypnotics, gamma-aminobutyric acid A (GABA(A)) receptor modulators, induces various side effects, including cognitive impairment, motor disturbance, dependence, tolerance, hangover, and rebound insomnia. Ramelteon (Rozerem; Takeda Pharmaceutical Company Limited, Osaka, Japan) is an orally active, highly selective melatonin MT(1)/MT(2) receptor agonist. Unlike the sedative hypnotics that target GABA(A) receptor complexes, ramelteon is a chronohypnotic that acts on the melatonin MT(1) and MT(2) receptors, which are primarily located in the suprachiasmatic nucleus, the body's "master clock." As such, ramelteon possesses the first new therapeutic mechanism of action for a prescription insomnia medication in over three decades. Ramelteon has demonstrated sleep-promoting effects in clinical trials, and coupled with its favorable safety profile and lack of abuse potential or dependence, this chronohypnotic provides an important treatment option for insomnia.

Prolonged-release melatonin for the treatment of insomnia in patients over 55 years

BACKGROUND

Clinical data show that poor quality, rather than quantity, of sleep corresponds negatively to measures of health, well-being and satisfaction with life. However, until now treatment of insomnia has primarily targeted quantity of sleep. PR (prolonged release)-melatonin offers a new treatment option in insomnia.

OBJECTIVES

To provide an overview of PR-melatonin, the first melatonin receptor agonist to be granted marketing authorisation in Europe as monotherapy for the treatment of primary insomnia in patients aged > 55 years.

METHODS

Review data published in peer review journals and the EMEA (European Medicines Agency) website.

RESULTS/CONCLUSION

PR-melatonin significantly improves morning alertness and quality of sleep compared with placebo. There are no safety concerns.

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.

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.

Complementary and alternative medicine for sleep disturbances in older adults

Complementary and alternative medicines (CAM) are frequently used for the treatment of sleep disorders, but in many cases patients do not discuss these therapies directly with their health care provider. There is a growing body of well-designed clinical trials using CAM that have shown the following: (1) Melatonin is an effective agent for the treatment of circadian phase disorders that affect sleep; however, the role of melatonin in the treatment of primary or secondary insomnia is less well established. (2) Valerian has shown a benefit in some, but not all clinical trials. (3) Several other modalities, such as Tai Chi, acupuncture, acupressure, yoga, and meditation have improved sleep parameters in a limited number of early trials. Future work examining CAM has the potential to significantly add to our treatment options for sleep disorders in older adults.

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.

Self-reported efficacy and tolerability of ramelteon 8 mg in older adults experiencing severe sleep-onset difficulty

BACKGROUND

Ramelteon is a selective MT(1)/MT(2) melatonin receptor agonist indicated for the treatment of insomnia characterized by difficulty with sleep onset.

OBJECTIVE

The current analysis was conducted to determine the effectiveness of ramelteon 8 mg in reducing the time to fall asleep in older adults with severe baseline sleep-onset difficulties.

METHODS

Patients with severe sleep-onset difficulty (defined as subjective sleep latency [sSL] > or =60 minutes) who had received ramelteon 8 mg or placebo were selected from a previously published multicenter outpatient trial of 829 older adults (aged > or =65 years) with primary, chronic insomnia (according to Diagnostic and Statistical Manual of Mental Disorders [Fourth Edition, Text Revision] criteria). Patients received single-blind placebo for 7 days (baseline) before receiving double-blind ramelteon 8 mg or placebo nightly for 5 weeks (35 nights). A 7-day, single-blind, placebo washout period followed. The primary end point was mean sSL for nights 1 through 7 (week 1). The mean changes in sSL from baseline at weeks 3 and 5 were evaluated to assess sustained efficacy. Adverse events (AEs) were collected in this analysis for both the ramelteon 8-mg and placebo groups.

RESULTS

A total of 157 patients from the rameltcon 8-mg group (mean age, 72.7 years; 87 women, 70 men) and 170 patients from the placebo group (mean age, 72.3 years; 111 women, 59 men) met the entry criteria for this post hoc analysis. Ramelteon 8 mg significantly reduced sSL at week 1 compared with placebo (change from baseline, -23.2 vs -7.5 minutes; P = 0.002). This statistically significant improvement was sustained at week 3 (-33.7 vs -19.8 minutes; P = 0.005) and week 5 (-37.4 vs -17.1 minutes; P < 0.001). The incidence of AEs was low. The most commonly reported treatment-emergent AEs were dizziness (ramclteon, 8.9%; placebo, 7.1%), dysgeusia (ramelteon, 7.0%; placebo, 2.9%), myalgia (ramelteon, 6.4%; placebo, 3.5%), and headache (ramelteon, 5.1%; placebo, 5.9%).

CONCLUSIONS

In this subset analysis of older adults with severe baseline sleep-onset difficulties, ramelteon 8 mg significantly and persistently reduced subjective reports of time to sleep onset during 5 weeks of nightly treatment. Ramelteon appeared to be an effective and well-tolerated treatment for these older adults with primary, chronic insomnia.

Disturbances in melatonin and core body temperature circadian rhythms after minimal invasive surgery

BACKGROUND

Sleep disturbances, fatigue and reduced general well-being frequently occur after minimal invasive surgery. The circadian rhythms of melatonin and core body temperature are central to the regulation of normal sleep. The aim of this study was to assess changes in these circadian rhythms after laparoscopic cholecystectomy.

METHODS

Twelve women were studied before and after laparoscopic cholecystectomy. The major urinary melatonin metabolite, 6-sulphatoxymelatonin (aMT6s), and the core body temperature were measured for 1 day before and 1 day after surgery. The basal and maximum secretion of aMT6s were determined, as well as the timing and amplitude of aMT6s and the temperature rhythm. The patients' rest-activity and calculated sleep parameters were assessed by actigraphy.

RESULTS

A significant delay in the timing of aMT6s rhythm was observed after surgery [median (range) peak time of aMT6s: after surgery, 05:49 h (02:57-08:23 h); before surgery, 04:32 h (02:18-06:49 h); P< or = 0.05]. The amplitude of the aMT6s rhythm was also significantly decreased after surgery [after surgery, 7.1 ng aMT6s/mg creatinine (1-15.9 ng); before surgery, 13.2 ng aMT6s/mg creatinine (2.9-22.7 ng); P< or = 0.005]. There was almost a 12-h phase delay of the core body temperature rhythm after surgery [peak time: before surgery, 17:39 h (15:17-22:06 h); after surgery, 05:14 h (03:24-21:43 h); P< or = 0.01].

CONCLUSIONS

Following laparoscopic cholecystectomy, there was a delay in the timing of the aMT6s rhythm and a decreased evening decline in the temperature rhythm.

Melatonin excretion levels and polysomnographic sleep parameters in healthy subjects and patients with sleep-related disturbances

BACKGROUND

The hormone melatonin plays a key role in the proper functioning of the circadian timing system (CTS). Exogenous melatonin has been shown to be beneficial in cases of CTS dysfunction and sleep disturbances. The aim of our study was to relate 24-h melatonin excretion to objective sleep measures.

METHODS

A total of 67 individuals were included in the study: 29 healthy subjects (16 women, 13 men; mean age 62.4 y, range 24-86) and 38 outpatients with neuropsychiatric sleep-related disturbances (25 women, 13 men; mean age 46.5 y, range 21-69). Over two consecutive nights in the sleep laboratory, polysomnographic (PSG) recordings were made and urine samples were collected at predefined intervals.

RESULTS

Our data failed to show any age-controlled partial correlation between 6-sulphatoxymelatonin (aMT6s) parameters and PSG parameters in either of the two groups.

CONCLUSION

Measuring endogenous melatonin does not seem to be an adequate way to evaluate sleep quality. This could be due to the fact that the size of the pineal gland and the amount of melatonin produced vary 20-fold between individuals.

Drug Insight: the use of melatonergic agonists for the treatment of insomnia-focus on ramelteon

Melatonin, a chronobiotic that participates in the control of the circadian system, is known for its sleep-promoting effects, which include shortening of sleep latency and lengthening of sleep duration. As a result of its short half-life, melatonin does not exhibit undesirable side effects, and its broad applicability for a variety of sleep problems has been the focus of numerous scientific studies. Melatonin has not, however, received regulatory approval from the US FDA as a drug, because it can be sold freely as a food supplement. Consequently, there has been an active search for patentable melatonin receptor ligands in recent years. Ramelteon, an agonist that acts solely on melatonin MT(1) and MT(2) receptors, is of particular interest, and preliminary research indicates that it holds considerable promise for clinical applications. Ramelteon has been shown to induce sleep initiation and maintenance in various animal models and in clinical trials. In chronic insomnia, ramelteon decreases sleep latency and increases total sleep time and sleep efficiency, without causing hangover, addiction or withdrawal effects. Ramelteon is thought to promote sleep by influencing homeostatic sleep signaling mediated by the suprachiasmatic nucleus. Although ramelteon's metabolism and pharmacokinetics differ from those of melatonin, its safety seems to be sufficient for short-term application. Its long-term effects remain to be determined.

Endogenous melatonin predicts efficacy of exogenous melatonin in consolidation of fragmented wrist-activity rhythm of adult patients with developmental brain disorders: A double-blind, placebo-controlled, crossover study

OBJECTIVE

: We studied whether the endogenous melatonin patterns in adult patients with developmental brain disorders have any role in response to exogenous melatonin given as a sleep-promoting medicine.

METHODS

: Participants included 15 adults (18-60 years, five females) with developmental brain disorders of varying etiologies, motor handicaps, and long-term history of sleep problems. According to the 24-h patterns of serum melatonin, patients were divided into two subgroups: lower and higher secretors. The pretreatment sleep disorder was characterized by a structured interview, 24-h ambulatory polysomnography and 7-day wrist actigraphy. Patients received 1, 3, or 6mg fast-release melatonin tablets, each for 4 weeks in increasing order, at a constant time of 30min before the desired sleep onset. Similarly, placebos with different codes were given during 3x4 weeks. The 7-day actigraphy was repeated at the end of each drug period. Outcome measures were six different parameters of non-parametric circadian rhythm analysis. Drug effects and 40 confounding/modulating factors were evaluated by applying two-level regression analyses with co-variables.

RESULTS

: Exogenous melatonin decreased the fragmentation of the rest-activity rhythm, increased the day/night ratio of activity and advanced the onset of rest period. The effects on fragmentation and day/night ratio were more pronounced in the lower than higher secretors of melatonin. Other contributing factors in the drug effects were blindness and some features of the original sleep disorder (disrupted cyclicity of the sleep architecture in polysomnography or reported daytime somnolence).

CONCLUSIONS

: Exogenous melatonin consolidated the fragmented rest-activity in about half of the patients. Low endogenous serum melatonin levels at night predicted improvement by the drug. Higher doses were not more effective than the lowest dose.

Disturbance and strategies for reactivation of the circadian rhythm system in aging and Alzheimer's disease

Circadian rhythm disturbances, such as sleep disorders, are frequently seen in aging and are even more pronounced in Alzheimer's disease (AD). Alterations in the biological clock, the suprachiasmatic nucleus (SCN), and the pineal gland during aging and AD are considered to be the biological basis for these circadian rhythm disturbances. Recently, our group found that pineal melatonin secretion and pineal clock gene oscillation were disrupted in AD patients, and surprisingly even in non-demented controls with the earliest signs of AD neuropathology (neuropathological Braak stages I-II), in contrast to non-demented controls without AD neuropathology. Furthermore, a functional disruption of the SCN was observed from the earliest AD stages onwards, as shown by decreased vasopressin mRNA, a clock-controlled major output of the SCN. The observed functional disconnection between the SCN and the pineal from the earliest AD stage onwards seems to account for the pineal clock gene and melatonin changes and underlies circadian rhythm disturbances in AD. This paper further discusses potential therapeutic strategies for reactivation of the circadian timing system, including melatonin and bright light therapy. As the presence of melatonin MT1 receptor in the SCN is extremely decreased in late AD patients, supplementary melatonin in the late AD stages may not lead to clear effects on circadian rhythm disorders.

Pharmacologic Management of Chronic Insomnia

Chronic insomnia is a common disorder that is under recognized, under diagnosed and under treated. Initial assessment should focus on identifying and treating, if present, any secondary causes of insomnia. Primary insomnia can be treated with behavioral and/or pharmacological therapy. A thorough sleep history can identify the type of insomnia present, its severity, and can consequently guide therapy. Behavioral therapy has been shown to be equivalent to or superior to pharmacologic therapy, at least in some patients. It is a reasonable initial approach, although there are barriers to its use. There are several pharmacologic agents available, some of which are more effective at reducing time to fall asleep and others for maintaining sleep. There is some evidence to indicate that combining the approaches may impair outcomes. There is little data on the long-term use of pharmacologic agents.

An Open-Label Study of Controlled-Release Melatonin in Treatment of Sleep Disorders in Children with Autism

Long-term effectiveness of controlled-release melatonin in 25 children, aged 2.6-9.6 years with autism without other coexistent pathologies was evaluated openly. Sleep patterns were studied using Children's Sleep Habits Questionnaire (CSHQ) and sleep diaries at baseline, after 1-3-6 months melatonin treatment and 1 month after discontinuation. Sleep diary and CSHQ showed a more problematic sleep in autistic children compared with controls. During treatment sleep patterns of all children improved. After discontinuation 16 children returned to pre-treatment score, readministration of melatonin was again effective. Treatment gains were maintained at 12 and 24-month follow-ups. No adverse side effects were reported. In conclusion, controlled-release melatonin may provide an effective and well-tolerated treatment for autistic children with chronic sleep disorders.

Repeated exposures to daytime bright light increase nocturnal melatonin rise and maintain circadian phase in young subjects under fixed sleep schedule

Effects of two different light intensities during daytime were examined on human circadian rhythms in plasma melatonin, core body temperature, and wrist activity under a fixed sleep schedule. Sleep qualities as indicated by polysomnography and subjective sleepiness were also measured. In the first week, under dim light conditions ( approximately 10 lx), the onset and peak of nocturnal melatonin rise were significantly delayed, whereas the end of melatonin rise was not changed. The peak level of melatonin rise was not affected. As a result, the width of nocturnal melatonin rise was significantly shortened. In the second week, under bright light conditions ( approximately 5,000 lx), the phases of nocturnal melatonin rise were not changed further, but the peak level was significantly increased. Core body temperature at the initial sleep phase was progressively elevated during the course of dim light exposure and reached the maximum level at the first night of bright light conditions. Subjective sleepiness gradually declined in the course of dim light exposure and reached the minimum level at the first day of bright light. These findings indicate that repeated exposures to daytime bright light are effective in controlling the circadian phase and increasing the peak level of nocturnal melatonin rise in plasma and suggest a close correlation between phase-delay shifts of the onset of nocturnal melatonin rise or body temperature rhythm and daytime sleepiness.

Searching for new options for treating insomnia: are melatonin and ramelteon beneficial?

Insomnia is one of the most common complaints faced in clinical practice. The limited pharmacological options available make the treatment of this complaint a challenge. All of the available benzodiazepines and non-benzodiazepine hypnotics have the potential to induce addiction, cause withdrawal symptoms, or trigger rebound insomnia. Further, the evidence supporting the utility of commonly prescribed options such as antidepressants and antipsychotics is limited. Melatonin is a hormone that has been associated with soporific effects. Based on this premise, a melatonin receptor agonist was created. Ramelteon was approved by the Food and Drug Administration in 2005 and is the only medication indicated for the long-term treatment of insomnia. A critical review with a clinical perspective of randomized, placebo-controlled clinical trials was conducted to determine the efficacy of melatonin and ramelteon for the treatment of insomnia. Based on this review, it appears that more placebo-controlled trials are indicated before valid judgments concerning the efficacy of both melatonin and ramelteon can be made. In the meantime, there is some support for the use of melatonin for the treatment of insomnia, and findings concerning ramelteon also appear promising. Nevertheless, clinicians who prescribe melatonin or ramelteon should be cautious and carefully monitor both potential benefits and adverse effects, since data on melatonin are based on studies with multiple limitations and only three controlled trials have been done with ramelteon.

Sleep Disturbance in Supportive Care of Cancer: A Review

Insomnia constitutes a significant source of suffering for patients with cancer as they move through the course of treatment and advanced illness. Practicing physicians and caregivers are challenged to address this troubling symptom without the benefit of an extensive literature specific to this population. There is evidence to suggest that the routine clinical management of patients with cancer with insomnia is discordant with best practices documented in the available literature. This paper reviews the literature to characterize the sleep disturbances experienced by patients with cancer. The evaluation and management of insomnia in patients with cancer is reviewed, and a management plan based on available literature is proposed.

Melatonin and sleep in aging population

The neurohormone melatonin is released from the pineal gland in close association with the light-dark cycle. There is a temporal relationship between the nocturnal rise in melatonin secretion and the 'opening of the sleep gate' at night. This association, as well as the sleep promoting effect of exogenous melatonin, implicates the pineal product in the physiological regulation of sleep. Aging is associated with a significant reduction in sleep continuity and quality. A decreased production of melatonin with age is documented in a majority of studies. Diminished nocturnal melatonin secretion with severe disturbances in sleep/wake rhythm has been consistently reported in Alzheimer's disease (AD). A recent survey on the effects of melatonin in sleep disturbances, including all age groups, failed to document significant and clinically meaningful effects of exogenous melatonin on sleep quality, efficiency and latency. However, in clinical trials involving elderly insomniacs and AD patients suffering from sleep disturbances exogenous melatonin has repeatedly been found to be effective in improving sleep. The results indicate that exogenous melatonin is more effective to promote sleep in the presence of a diminished production of endogenous melatonin. A MT1/MT2 receptor analog of melatonin (ramelteon) has recently been introduced as a new type of hypnotics with no evidence of abuse or dependence.

Melatonin for sleep disturbances in Parkinson's disease

BACKGROUND AND PURPOSE

Many patients with Parkinson's disease (PD) experience sleep-related symptoms. Studies in other populations indicate that melatonin can increase sleep efficiency, decrease nighttime activity, and shorten sleep latency, but there has been little research on the use of melatonin in PD. The purpose of this study was to compare the effects of two doses of melatonin to placebo on sleep, daytime sleepiness, and level of function in patients with PD who complained of sleep disturbances.

PATIENTS AND METHODS

A multi-site double-blind placebo-controlled cross-over trial was employed; 40 subjects completed the 10-week protocol. There was a 2-week screening period, 2-week treatment periods, and 1-week washouts between treatments. Nocturnal sleep was assessed by actigraphy and diaries, whereas daytime sleepiness and function were assessed by the Epworth Sleepiness Scale (ESS), Stanford Sleepiness Scale (SSS), and General Sleep Disturbance Scale (GSDS).

RESULTS

Repeated measures analysis of variance revealed a significant improvement in total nighttime sleep time during the 50 mg melatonin treatment compared to placebo. There was significant improvement in subjective sleep disturbance, sleep quantity, and daytime sleepiness during the 5 mg melatonin treatment compared to placebo as assessed by the GSDS.

CONCLUSIONS

Although we found a statistically significant improvement in actigraphically measured total sleep time on 50 mg melatonin compared to 5 mg or placebo, this small improvement (10 min) may not be clinically significant. However, the significant improvement found in subjective sleep disturbance suggests that these modest effects may be clinically relevant in this patient population.

Effects of exogenous melatonin on sleep: a meta-analysis

Exogenous melatonin reportedly induces drowsiness and sleep, and may ameliorate sleep disturbances, including the nocturnal awakenings associated with old age. However, existing studies on the soporific efficacy of melatonin have been highly heterogeneous in regard to inclusion and exclusion criteria, measures to evaluate insomnia, doses of the medication, and routes of administration. We reviewed and analyzed (by meta-analysis) available information on effects of exogenous melatonin on sleep. A MEDLINE search (1980 to December 2003) provided English-language articles, supplemented by personal files maintained by the authors. The analysis used information derived from 17 different studies (involving 284 subjects) that satisfied inclusion criteria. Sleep onset latency, total sleep duration, and sleep efficiency were selected as the outcome measures. The study effect size was taken to be the difference between the response on placebo and the mean response on melatonin for each outcome measured. Melatonin treatment significantly reduced sleep onset latency by 4.0 min (95% CI 2.5, 5.4); increased sleep efficiency by 2.2% (95% CI 0.2, 4.2), and increased total sleep duration by 12.8 min (95% CI 2.9, 22.8). Since 15 of the 17 studies enrolled healthy subjects or people with no relevant medical condition other than insomnia, the analysis was also done including only these 15 studies. The sleep onset results were changed to 3.9 min (95% CI (2.5, 5.4)); sleep efficiency increased to 3.1% (95% CI (0.7, 5.5)); sleep duration increased to 13.7 min (95% CI (3.1, 24.3)).

Melatonin as a hypnotic: pro

In diurnal species, nocturnal melatonin secretion coincides with the habitual hours of sleep, in contrast to nocturnal animals which are at the peak of their activity while producing melatonin. Studies in humans, diurnal non-human primates, birds and fish show that melatonin treatment can facilitate sleep initiation during the daytime or improve altered overnight sleep. Behaviorally, the sleep-promoting effects of melatonin are distinctly different from those of common hypnotics and are not associated with alterations in sleep architecture. The effects of melatonin on sleep are mediated via specific melatonin receptors and physiologic doses of the hormone, those inducing circulating levels under 200 pg/ml, are sufficient to promote sleep in diurnal species. Aging reduces responsiveness to melatonin treatment and this correlates with reduced functional potency of melatonin receptors. Since melatonin receptors are present in different tissues and organs and involved in multiple physiologic functions, using physiologically relevant doses (0.1-0.3 mg, orally) and time of administration (at bedtime) is recommended, in order to avoid known and unknown side effects of melatonin treatment.

Melatonin as a hypnotic: con

The physiological roles of melatonin are still unclear despite almost 50 years of research. Elevated melatonin levels from either endogenous nocturnal production or exogenous daytime administration are associated in humans with effects including increased sleepiness, reduced core temperature, increased heat loss and other generally anabolic physiological changes. This supports the idea that endogenous melatonin increases nocturnal sleep propensity, either directly or indirectly via physiological processes associated with sleep. The article "Melatonin as a hypnotic--Pro", also in this issue, presents evidence to support this viewpoint. We do not entirely disagree, but nevertheless feel this is an overly simplistic interpretation of the available data. Our interpretation is that melatonin is primarily a neuroendocrine transducer promoting an increased propensity for 'dark appropriate' behavior. Thus, it is our view that exogenous melatonin is only hypnotic in those species or individuals for which endogenous melatonin increases sleep propensity and is consequently a dark appropriate outcome. Evidence supporting this position is drawn primarily from studies of exogenous administration of melatonin and its varied effects on sleep/wake behavior based on dose, time of administration, age and other factors. From this perspective, it will be shown that melatonin can exert hypnotic-like effects but only under limited circumstances.

Sleep Disorders in the Older Patient

Sleep changes dramatically with old age. Subjective and objective measures demonstrate an increase in sleep and wake disturbances with advancing age. The older person has a more fragmented sleep, sleeps less deeply, and tends to experience early morning awakenings. When older patients have sleep disorders, they often present with excessive daytime sleepiness, insomnia, or abnormal motor activity. In making the appropriate diagnosis, the role of the provider is to review the patient's medical history,psychiatric history, medications, underlying medical illnesses, and sleep-wake pattern. The aging process itself does not cause sleep problems and sleep requirements do not decrease with advanced age. The prevalence of insomnia, sleep-related breathing disorder, PLMS, and RLS increases with age and may lead to poor sleep quality. Because many sleep disorders are potentially reversible, it is the responsibility of the primary care provider to screen for these problems. A carefully planned clinical decision-making process when encountering a sleep disturbance in the older patient can greatly enhance quality of life and daytime function.

Improvement of sleep quality by controlled-release melatonin in benzodiazepine-treated elderly insomniacs

Benzodiazepines are widely used in the elderly population for the initiation of sleep. However, very frequently, complaints about poor sleep maintenance persist despite benzodiazepine treatment. Melatonin, a hormone produced by the pineal gland at night, is involved in the regulation of the sleep/wake cycle. Melatonin production decreases with age and can also be inhibited by benzodiazepines. We have recently reported on the association between insomnia and impaired melatonin output in the elderly. In the present study we have investigated the efficacy of melatonin replacement therapy in improving sleep in 21 elderly subjects who have been taking benzodiazepines and had low melatonin output. In a randomized, double-blind, crossover designed study the subjects were treated for three weeks with 2 mg per night of controlled-release melatonin and for 3 weeks with placebo, 2 h before desired bedtime with a 1-week washout period between treatment periods. Subjects' sleep was assessed by wrist actigraphy. Melatonin treatment significantly increased sleep efficiency and total sleep time and decreased wake after sleep onset, sleep latency, number of awakenings and fragmental index, as compared to placebo. The results of our study indicate that melatonin replacement therapy can improve sleep quality in the elderly and that the beneficial effects are augmented in the presence of benzodiazepines.

Advances in the management of insomnia

Insomnia is a prevalent disorder, altering night time sleep, daytime mood and performance. Current treatment strategies, used separately or in combination, include pharmacological, circadian, behavioural and cognitive therapy. An increased diversity of available hypnotics with different potency, pharmacodynamic and pharmacokinetic profiles and improved side effect profiles provides more flexibility in designing individual treatment strategies. Melatonin, a pineal hormone with acute sleep-promoting and chronobiotic properties, allows additional possibilities in treating insomnia and circadian sleep disorders. Current studies of processes involved in normal sleep regulation and pathophysiology of insomnia should result in the development of new medications based on physiological mechanisms of sleep.

Melatonin receptors: potential targets for central nervous system disorders

The pineal hormone melatonin has become the subject of considerable speculation in both the scientific and lay press. Media coverage, coupled with scientific interest fuelled by the recent molecular cloning of a family of melatonin receptors, has led to a renaissance in melatonin research. While numerous physiological effects have been attributed to melatonin, the lack of selective agonists and antagonists for individual melatonin receptor subtypes has hampered progress towards the elucidation of the roles of these receptors. This review focuses on the molecular and pharmacological characterisation of melatonin receptors, the possible clinical utility of melatonin receptor ligands, and the progress towards the identification of selective ligands for these receptors.

Basic aspects of melatonin action

Melatonin is synthesized and secreted during the dark period of the light-dark cycle. Thus, melatonin has an obvious association with sleep, at least in diurnal animals. Rhythmic nocturnal melatonin secretion is directly generated by the circadian clock, located in mammals within the suprachiasmatic nuclei (SCN), and is entrained to a 24-h period by the light-dark cycle. The periodic secretion of melatonin may be used as a circadian mediator to any system than can "read" the message. In addition, direct effects of the hormone on the SCN could explain some of melatonin effects on the circadian system. Duration of melatonin nocturnal secretion is directly proportional to the length of the night and it has been demonstrated experimentally to be the critical parameter for photoperiod integration. The two main hypotheses to explain the action of melatonin are the duration hypothesis (supporting that night length is coded by the duration of the melatonin secretory phase) and the coincidence hypothesis (holding that physiological responses are linked to the existence of a diurnal rhythm in sensitivity to melatonin). The sites and mechanisms of action of melatonin for circadian and photoperiodic responses are far from being elucidated, but action through specific membrane receptor sites is well documented. In view of melatonin s lipophilic nature, interactions with specific intracellular proteins like calmodulin or tubulin, or with nuclear receptor sites, have also been considered, whereas the physiological significance of the documented antioxidant effect of melatonin remains to be settled. Melatonin seems to act as an "arm" of the circadian clock, giving a time-related signal to a number of body functions; one of these, the circadian organization of an organism's defence, is discussed in some detail as an example.