Light and Melatonin Can Reset Circadian Rhythm

By Salodof, Macneil Jane | Clinical Psychiatry News, May 2008 | Go to article overview

Light and Melatonin Can Reset Circadian Rhythm


Salodof, Macneil Jane, Clinical Psychiatry News


SCOTTSDALE, ARIZ. -- Before traveling from California to South Africa, Dr. Alon Y. Avidan prepared for the time change by spending afternoons in his office, out of the sun. After he arrived in South Africa, he awoke between 5 a.m. and 7 a.m. every morning and took a walk for an hour or more in bright sunlight.

"In a few days, I was on South African time," he told those attending a meeting on sleep medicine sponsored by the American College of Chest Physicians.

Light therapy can be highly effective in correcting jet lag and other circadian rhythm disorders, according to Dr. Avidan, medical director of the University of California, Los Angeles, neurology clinic and associate director of UCLA's sleep disorders center.

Melatonin, a dietary supplement with no approved medical indications, is another useful treatment when delayed sleep is a problem, he said, and ramelteon (Rozerem) shows promise. Although ramelteon is approved only for insomnia, Dr. Avidan said he prescribes it off label to patients with the type of circadian rhythm disorder that causes night owls to complain they can't fall asleep at normal bedtimes or wake up early in the morning.

Often they are tired all day, but not at night, with detriment to their quality of life. "Circadian-related disruption leads to insomnia, hypersomnia, or both," he said, and it can cause impairment of social, oc- cupational, or other areas of functioning.

Sunlight is the most powerful external time cue for regulating and synchronizing the body's circadian rhythms with the environment, Dr. Avidan said. It promotes wakefulness as input from the retina goes to the suprachiasmatic nucleus (SCN) of the hypothalamus, which contains a circadian pacemaker.

To opposite ends, the pineal gland releases melatonin in response to darkness. Melatonin promotes sleep, but levels of it decrease with aging. Compensating with the dietary supplement has been shown to help advance the circadian clock, according to Dr. Avidan.

For patients with delayed sleep phase, he recommended ex- posure to bright light--as much as 10,000 amps--in the early morning and taking 0.5 mg of melatonin 5-7 hours before the patient's habitual sleep time, or 12-14 hours before the time a person wishes to awake.

In response to an audience question, Dr. Avidan said several small studies not yet published suggest ramelteon also can advance sleep time. It acts on the melatonin receptors MT1 and MT2, he noted, and described ramelteon as "a true drug." When using ramelteon off label for a circadian sleep disorder, he prescribes a 4-mg dose (which is half the 8-mg dose approved for insomnia).

Advanced sleep-phase disorder is often seen in poorly lit nursing homes, according to Dr. …

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