Differences between light and sound sleepers in the residual effects of nitrazepam

1 Residual effects of nitrazepam 2.5, 5 and 10 mg, and lactose dummy administered at night (23.00 h) on performance and subjective effects the following day, were measured in two groups, ten sound sleepers and ten light sleepers. Treatments were given orally at weekly intervals in a balanced order with double-blind conditions. 2 Auditory vigilance of sound sleepers was unaffected by treatments. Light sleepers, by contrast, showed significant ( P < 0.05) improvement after nitrazepam (5 mg) and impairment after 10 mg. 3 Auditory reaction time was prolonged after nitrazepam (10 mg) in light sleepers and also by 5 mg in the sound sleepers. Tapping, short term memory and digit symbol substitution were all impaired by nitrazepam (10 mg) but there was no difference in response of the two groups. 4 Mental sedation was rated higher by light sleepers after lactose than by sound sleepers. After nitrazepam (10 mg) sound sleepers had significantly higher ratings than after lactose, but light sleepers did not. Ratings of mental sedation indicated that after nitrazepam (2.5 mg) light sleepers were more alert than after lactose, and after both 2.5 and 5.0 mg they were more alert than after nitrazepam (10 mg). 5 The implications of the findings that subjects with unsatisfactory sleep patterns may be rendered more alert, and perform certain prolonged monotonous tasks more efficiently, after an optimal dose of hypnotic are discussed.