TUESDAY, Dec. 2 (HealthDay News) -- The experimental drug tasimelteon helps treat temporary insomnia caused by jet lag or night shifts, according to the results of two new clinical trials.

The phase II study included 39 people randomly assigned to receive either 10 milligrams, 20 mg, 50 mg or 100 mg of tasimelteon, or a placebo. They were monitored for seven nights -- three at baseline, three after a five-hour advance of sleep-wake schedule with treatment before sleep, and one night after treatment.

The phase III trial included 411 people who had transient insomnia induced in a sleep clinic by a five-hour advance of their sleep-wake cycle. They received either 20 mg, 50 mg, or 100 mg of tasimelteon, or a placebo, 30 minutes before bedtime.

The patients in the trials were monitored to determine their sleep efficiency (amount of actual sleep during their time in bed) and sleep latency (time it took them to fall asleep). Compared to placebo, tasimelteon (a melatonin analogue) improved sleep efficiency and reduced sleep latency, according to the researchers. They also found that patients taking tasimelteon showed an earlier shift in plasma melatonin rhythm.

The findings were published online and in an upcoming print issue of the The Lancet.

"The development of melatonin analogues, which specifically target melatonin receptors, will also help us to understand more about the role of the hormone melatonin in the regulation of sleep," the American and Australian researchers said in a journal news release.

"By simultaneously improving sleep latency and sleep maintenance with a shift in circadian rhythms, tasimelteon has the potential for the treatment of patients with transient insomnia associated with circadian rhythm sleep disorders, including people affected by jet leg, or those who work at night, and early-riser workers," the study authors concluded.

More information

The U.S. National Sleep Foundation has more about shift work.