Sleep-inducing pharmaceuticals: a comparison of melatonin, zaleplon, zopiclone, and temazepam

Current military operations often require pharmaceutical methods to sustain alertness and facilitate sleep in order to maintain operational readiness. This study was designed to compare the sleep-inducing power of four medications.

There were 9 men and 14 women, ages 21-53 yr, who were assessed for psychomotor performance before and for 7 h after ingestion of a single dose of placebo, zaleplon 10 mg, zopiclone 7.5 mg, temazepam 15 mg, or time-released melatonin 6 mg. The experimental design was a double-blind crossover with counterbalanced treatment order. Subjects wore polysomnographic electrodes to record total sleep and sleep latency during 4-min periods with eyes closed immediately before and after each psychomotor test sequence. Subjective drowsiness was assessed by questionnaire.

There were drug x trials interactions for zaleplon, zopiclone, and temazepam for total sleep, sleep latency, and subjective drowsiness. More sleep, shorter sleep latency, and more drowsiness occurred immediately after psychomotor testing compared to before testing for all medications. Melatonin did not cause any sleep prior to psychomotor testing sessions, but caused sleep and reduced sleep latency after psychomotor test sessions from 1 3/4 h to 4 3/4 h post-ingestion.

The sleep-inducing power of the medications before psychomotor testing was zopiclone > zaleplon > melatonin > temazepam. The corresponding effect after psychomotor testing was zopiclone > melatonin > zaleplon > temazepam.