The effects of chlormethiazole in EEG recorded sleep in normal elderly volunteers.

Chlormethiazole has sedative, hypnotic and anticonvulsant properties, and is used in the treatment of sleep disorders and confusion in the elderly. In this study we examined the effects of chlormethiazole on EEG recorded sleep in six normal volunteers aged 67-74 years. After baseline registration, chlormethiazole (base), 384 mg p.o. (i.e. 2 capsules), was administered during 5 nights followed by one withdrawal registration. Sleep latency decreased from 52 to 27 min during the treatment period (P less than 0.01) and increased to 57 min during withdrawal. Wakeful periods during sleep decreased from 106 to 62 min during the treatment period and increased during withdrawal to 104 min (P less than 0.001). The sleep efficiency improved slightly during chlormethiazole treatment. The distribution of the sleep stages was essentially unaffected by chlormethiazole. According to subjective assessment the subjects rated their ability to fall asleep and their sleep quality as significantly better during the drug period. Based on sleep recordings and subjective ratings, there was no evidence of rebound insomnia on withdrawal. Psychoperformance tests revealed no evidence of hangover effects.