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Drug used to beat sleepless nights

Night-shift workers having trouble sleeping may find some peace with a new insomnia drug, studies have shown.

Phase II and III trials found the melatonin analogue tasimelteon was effective in dealing with transient insomnia of the kind typically caused by night shifts and jet lag.

Circadian rhythm sleep disorders are common causes of insomnia that affect millions of people worldwide. These come in the form of persistent and recurrent sleep disturbances, insomnia when trying to sleep, and excessive sleepiness while trying to remain awake. They often occur when sleep times are out of sync with the body's circadian rhythms.

During the phase II and phase III randomized, placebo-controlled studies, patients' sleep efficiency was determined by calculating the amount of sleep they got as a percentage of the time they spent in bed. Their sleep latency, the time it took for them to fall asleep, was also recorded. The shift in the timing of the internal biological clock was assessed by measuring the plasma melatonin rhythm.

The studies showed tasimelteon reduced sleep latency and improved sleep efficiency compared with placebo. The plasma melatonin rhythm was shifted earlier with tasimelteon compared with the placebo.

The authors of the article, Dr Shantha Rajaratnam of Harvard Medical School and Dr Elizabeth Klerman of Monash University, wrote: "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."

Copyright © Press Association 2008