In previous studies it has been found out that melatonin is not effective in treating secondary sleep disorders or preventing jet lag but when taken orally to regulate sleep disorders, lowers the blood pressure in women.

A new study done by researchers from the Divisions of Sleep Medicine at Brigham and Women's Hospital and Harvard Medical School showed that melatonin, when taken orally during non-typical sleep times, significantly improves a person's ability to sleep. Such a finding is especially important to workers with rotating or night shifts, travelers with jet lag and people with advanced or delayed sleep phase syndrome.

Melatonin is a hormone produced by the body at night in darkness, which helps the brain determine day and night to help regulate sleep cycles and circadian timing. Retinal light exposure inhibits the release of the hormone.

Millions of Americans take melatonin supplements to improve their sleep, yet the results of prior studies on the efficacy of melatonin as a sleep-promoting agent have been mixed, according to the Agency of Healthcare Research and Quality, which carried out an extensive review of this topic two years ago. The present study, conducted at the Brigham and Women's Hospital, sought to address this question.

This study appears in the May 1, 2006 issue of the journal Sleep.

Read more at Rush University Medical Center.