Modulation of delta activity by hypnotics in middle-aged subjects: studies with a benzodiazepine (flurazepam) and a cyclopyrrolone (zopiclone).

Period crossing analysis was used to study the effects of flurazepam (30 mg) and zopiclone (5, 7.5, and 10 mg) on delta wave activity (0.5-2.0 Hz) during the first 4 h of sleep in middle-aged subjects. The drugs do not affect the visual scoring of slow wave sleep in middle age, but modification of delta activity does occur. Mean amplitude of delta wave activity over the 4-h period was reduced by both drugs, while the total number of delta waves and their mean period increased. The number of high-amplitude delta waves (greater than 60 microV) was decreased by the drugs, and those of low amplitude (10-60 microV) increased. Power in the frequency band 1.2-2.0 Hz was reduced.