Dose determinants of rebound insomnia.

A polysomnographic assessment in healthy normal sleepers of possible dose relations for rebound insomnia was conducted. As an additional measure of rebound the study included a direct test of sleep/wake tendency during the night of drug discontinuation. Twelve, healthy men (21-30 years) each received placebo, 0.25 mg and 0.50 mg triazolam for 6 consecutive nights followed by a discontinuation night and 14 nights of recovery at home. The three conditions were presented, double-blind, in a latin square design. On night 6 of drug administration both doses increased total sleep time compared to placebo, but 0.50 mg did not improve sleep beyond 0.25 mg. On drug discontinuation (night 7) wake time over the 8 h recording and sleep latency after an experimental awakening (02.30 h) were increased with 0.50 mg compared to placebo and 0.25 mg. On these measures of rebound 0.25 mg did not differ from placebo. Thus rebound insomnia occurred only at a dose (0.50 mg) which produced no additional hypnotic efficacy in these normal sleepers. Whether tests of sleep/wake tendency make a useful measure of rebound insomnia needs further clarification.