Our bodies produce melatonin in the dark. Yet without enough bright light in the day, our chronobiological circadian rhythm is disturbed. This causes an imbalance in our hormones including melatonin secretions.
Melatonin improves SAD patients
"In a report to appear online this week in the Proceedings of the National Academy of Science, researchers at Oregon Health & Science University (OHSU) show that the hormone melatonin effectively treats seasonal affective disorder (SAD), a form of depression that occurs during winter months when sunlight is reduced. The disorder is currently treated with bright light exposure.
Alfred Lewy, MD, PhD, who is OHSU School of Medicine’s Richard H. Phillips Professor of Biological Psychiatry, senior vice chairman of psychiatry, and director of the Sleep and Mood Disorders Lab, and who has pioneered research in circadian rhythm disturbances, led the current study. Dr Lewy’s team sought to determine whether depression results from a misalignment of circadian rhythms with the sleep/wake cycle that occurs during winter. Circadian rhythms can be tracked to the later dawn or earlier dusk of the winter months.
Dr Lewy’s team compared melatonin’s effect when taken during the morning than melatonin taken in the afternoon. Sixty-eight patients with seasonal effective disorder received low-dose melatonin or a placebo during morning or afternoon for three weeks.
After several years of research, the team concluded that, similar to jet lag, circadian misalignment is a major factor in seasonal affective disorder. Melatonin worked best if taken in the afternoon or evening in the majority of patients who were phase-delayed “night-owl” types, while another group of “morning lark” phase-advanced patients responded better to melatonin if it was taken in the morning. The dose of melatonin taken was low enough not to cause day-time drowsiness.
Although low-dose, sustained-release melatonin may be effective for SAD, “People in the phase-advanced subgroup should use these treatments at different times of the day than the typically phase-delayed type of patient," explained Dr. Lewy."