People who live in the Northern Hemisphere experience significant seasonal changes in climate and the duration of daylight. In some cases, the change in the cycle between light and darkness can affect your sleep/wake cycle. Mood changes that occur seasonally are termed seasonal affective disorder, or SAD. Melatonin supplements may be an option for treating mood symptoms related to seasonal changes. Always consult your physician before using any alternative remedy to treat a serious health condition.
Seasonal Affective Disorder
It is estimated that approximately 5 percent of the U.S. population suffers from seasonal affective disorder. An additional 10 to 20 percent may experience milder symptoms of the disorder. Symptoms of seasonal affective disorder include loss of appetite, weight gain, lethargy, fatigue, anxiety, irritability and depression. Although SAD is more common during the winter months, people may experience seasonal affective disorder in the summer as well.
Melatonin
The pineal gland at the center of the brain secretes a hormone called melatonin in response to changes in daylight. As daylight fades, melatonin production is increased. Conversely, an abundance of daylight suppresses melatonin production. In many ways, melatonin is responsible for maintaining normal cycles of sleep, waking and alertness.
Significance
It has been hypothesized that changes in the duration of daylight as the seasons change disrupts normal circadian rhythm cycles. Melatonin production may either be stimulated too early, or delayed. As sleep and alertness cycles move out of sync, some people may begin to experience symptoms of seasonal affective disorder. Although symptoms are unlikely to be life-threatening, they can have negative social and occupational effects.
Expert Insight
According to the "Proceedings of the National Academy of Sciences," Alfred Lewy and colleagues examined the effects of melatonin on depression symptoms that occurred during winter months. The results of the study suggested that the normal interval between melatonin secretion and the middle of sleep is six hours. As a result of a later dawn in winter months, melatonin production is delayed, shortening this interval. The study found that patients who took melatonin in the afternoon, thus lengthening the interval between melatonin and sleep closer to six hours, reported improvement in depression symptoms.
Warning
Always consult a physician before using melatonin. Although generally safe, melatonin may exacerbate seizure and bleeding disorders. In addition, melatonin can cause disorientation and worsen mood disorders. Pregnant and nursing mothers should avoid melatonin, because there is insufficient safety data for use in these populations.
References
- Family Doctor: Seasonal Affective Disorder
- MayoClinic.com: Melatonin
- University of Maryland Medical Center: Melatonin
- "The Circadian Basis of Winter Depression," Proceedings of the National Academy of Sciences. Lewy AJ, Lefler BJ, Emens JS, Bauer VK. (Apr. 2006).
