The aim of this placebo controlled study is to investigate the effect of 2 mg melatonin Slow Release (Circadin®) on the sleep/wake cycle in elderly insomniac out-subjects, aged 55 years or more.

Circadin® is a newly developed slow release galenic formulation of melatonin, producing overall levels of melatonin comparable to those observed in a control population, when administered to patients with deficiency in melatonin; thus it deserves more clinical and paraclinical investigations for establishing efficacy in inducing and maintaining sleep and for safety. Since, on the one hand, the endogenous substance melatonin has beneficial effects on sleep in man and, on the other hand, there is a decrease in melatonin secretion in elderly people, substitution therapy in elderly insomniacs would be a desirable therapy.

The aim of this placebo controlled study was to investigate the effect of 2 mg Melatonin Slow Release (Circadin®) on the sleep/wake cycle in elderly insomniac out-subjects, aged 55 years or more. Sleep was assessed by means of polysomnography (hypnographic results), all-night sleep EEG spectral analysis (functional and quantitative results of sleep EEG), actimetry (SomnitorTM), wake EEG and sleep/wake quality questionnaires. Vigilance and cognitive skills were assessed by means of psychomotor and neurocognitive tests derived from the Leeds psychomotor test battery (vigilance and arousal) and TEA battery (attention).

Inclusion Criteria:

• Healthy male and female, aged ≥ 55 years, suffering from primary insomnia according to DSM-IV criteria (307.42)

Exclusion Criteria:

• According to DSM-IV, subjects belonging to the following groups are excluded: 780.59; 307.45; 307.47; 780.xx (Appendix 2);
• Use of benzodiazepines or other hypnotics during the preceding 1 month with a frequency of more than 2 times a week and lasting more than 2 weeks;
• Severe neurological, psychiatric or sleep disorders;
• Other serious diseases;
• Taking more than 1/2 l of alcohol, more than 3 cups of coffee or more than 10 cigarettes per day .
• Subjects who need beta blockers as a treatment.