Study to Investigate the Effects of Melatonin, Temazepam & Zolpidem on Sleep EEG in Men and Women

This study has been designed to compare the effects of melatonin with those of drugs (temazepam and zolpidem) regularly prescribed for the treatment of insomnia, in healthy, middle-aged volunteers. The study will take place at one centre. Volunteers consenting to participate in the study will have their eligibility confirmed by a screening panel, including spending one night in the sleep clinic to acclimatize to the study procedures. Blood and urine samples will be collected during this overnight visit. Volunteers continuing to remain eligible will receive, in turn, melatonin, temazepam, zolpidem and placebo as a single dose during 4 treatment phases lasting one night and separated by at least five days. Neither the volunteer nor the study staff will be aware of which drug each volunteer is receiving at each treatment phase. The volunteer's electrical brain activity will be measured whilst sleeping. Other aspects of sleep, including measures of sleep quality, will also be measured. Urine samples will be collected during each treatment phase. Volunteers will undergo an assessment of health prior to departure from the clinic at their last treatment phase, and study staff will telephone 2 weeks later to obtain further information on their health status. The primary study objective is to compare EEG power spectra during nonREM sleep in the slow-wave frequencies following administration with melatonin to temazepam.