Relief for Winter Depression
Depression that Comes and Goes
Seasonal affective disorder, also known as SAD, is a type of depression that comes and goes with the seasons and correlates to the amount of light a person receives. A study by researchers at Oregon Health and Science University (OSHU) suggests that melatonin, a natural substance in the brain, can give relief for winter doldrums.
This research project was led by Alfred Lewy, M.D., Ph.D., a recognized expert in the international sphere of circadian or 24 hour rhythm disturbances also experienced by air travelers, shift workers, and the blind.
The OHSU Sleep and Mood Disorders Lab, headed by Lewy and his colleagues, tested the theory that short winter days cause a misalignment of circadian physiological rhythms with the sleep/wake cycle, causing depression in some people. With winter comes a later dawn, resulting in a circadian phase delay in sleep patterns. This is similar to what we experience when air travel takes us in a western direction. Some people track to the earlier dusk of winter, which causes the same amount of misalignment but in what is known as the phase-advance direction. The severity of the symptoms experienced is the same in both cases of misalignment.
Treatment for most SAD patients has been exposure to bright light, which brings on phase advances when exposure occurs during morning hours. Melatonin is also effective in bringing about phase advances, but needs to be taken in the afternoon. Lewy and his colleagues employed afternoon melatonin to test if its antidepressant properties were greater than when taken in the morning, which brings on phase delays.
68 Patients were assigned at random to one of three treatment groups who were treated with melatonin or placebo capsules in the morning or afternoon for a period of three weeks. After four years of research, the conclusion is that as in persistent jet lag, circadian misalignment is the major component of SAD.
Night Owl or Morning Lark?
Those phase-delayed type patients, or "night owls," have a misalignment that responds best to a low afternoon or evening dose of melatonin. A second group of SAD patients, called "morning larks," responded best to taking low morning doses of melatonin.
Once low-dose, sustained-release melatonin becomes available, this will be an important treatment option in addition to the current treatment of bright light exposure for patients with SAD. "However," explains Lewy, "people in the phase-advanced subgroup should use these treatments at different times of the day than the typically phase-delayed type of patient."