Melatonin May Play a Role in the Winter Blues
The mood-altering effects of seasonal affective disorder (SAD) may be due in part to prolonged secretion of melatonin in the brain during the winter, according to a new report in the Archives of General Psychiatry.1 While the cause of SAD is not clear, it appears that the reduced amount of daylight from shorter winter days contributes to the condition. This tends, therefore, to be more of a problem for people living in higher latitudes, such as Seattle, Washington, or Oslo, Norway, where winter sunlight is less compared with southern regions.2 Symptoms of SAD include depression, weight gain, increased sleep, or overeating, and usually occur only in the fall or winter.
The researchers examined the timing and amount of melatonin released over a 24-hour period in 55 people with SAD and 55 healthy volunteers, in both the summer and winter. Participants were kept in a dimly lit room, where blood levels of melatonin were measured every 30 minutes. The authors found that, in people with SAD, the duration of active nighttime melatonin secretion was 38 minutes longer in the winter than in the summer. However, in people without SAD, there was no difference between winter and summer, with regard to the duration of nocturnal melatonin secretion. Thus, individuals with SAD have a seasonal change in melatonin secretion that does not occur in normal individuals. This response is similar to the changes that occur in some mammals in response to seasonal changes in sunlight exposure.
Although changes in melatonin secretion may be a marker for SAD, scientific studies using supplemental melatonin have been inconclusive. While one small study found that 125 mcg of melatonin taken twice daily was effective at reducing the depressive symptoms of SAD,3 other studies have shown melatonin to be an ineffective treatment.4 5 More research is needed to determine whether supplementing with melatonin is helpful for SAD.
Other nutritional supplements may help combat the symptoms of SAD. The amino acid L-tryptophan has been shown in a few small trials to be an effective treatment for SAD.6 7 Tryptophan is a precursor for serotonin, a chemical in the brain that is believed to play a role in preventing SAD. Currently, L-tryptophan is available by prescription only. It is unclear whether its derivative, 5-hydroxytryptophan (5-HTP), which is sold over-the-counter, is equally effective. Supplementing with vitamin D3 may also improve depression associated with SAD. One study found that 400–800 IU of vitamin D per day helped elevate mood in late winter in healthy individuals.8 In another controlled trial, one-time administration of 100,000 IU of vitamin D led to a significant improvement in depression.9 However, due to potential toxicity, this large an amount of vitamin D should be used only under the supervision of a physician.
There is some preliminary evidence that taking 300 mg of St. John’s wort three times per day may be useful in treating SAD.10 11 However, some of the patients in these studies used bright-light therapy, a well-established treatment for SAD which may have been responsible for some of the reported improvement. Nonetheless, St. John’s wort is relatively safe at the levels tested and may be beneficial for people with SAD.
1. Wehr TA, Duncan Jr. WC, Sher L, et al. A circadian signal of change of season in patients with seasonal affective disorder. Arch Gen Psychiatry 2001;58:1108–14.
2. Magnusson A. An overview of epidemiological studies on seasonal affective disorder. Acta Psychiatr Scand 2000;101:176–84.
3. Lewy AJ, Bauer VK, Cutler NL, Sack RL. Melatonin treatment of winter depression: a pilot study. Psychiatr Res 1998;77:57–61.
4. Wirz-Justice A, Graw P, Krauchi K, et al. Morning or night-time melatonin is ineffective in seasonal affective disorder. Psychiatr Res 1990;24:129–37.
5. Rosenthal NE, Sack DA, Jacobsen FM, et al. Melatonin in seasonal affective disorder and phototherapy. J Neural Transm Suppl 1986;21:257–67.
6. McGrath RE, Buckwald B, Resnick EV. The effect of L-tryptophan on seasonal affective disorder. J Clin Psychiatry 1990;51:162–3.
7. Ghadirian AM, Murphy BE, Gendron MJ. Efficacy of light versus tryptophan therapy in seasonal affective disorder. J Affect Disord 1998;50:23–7.
8. Lansdowne AT, Provost SC. Vitamin D3 enhances mood in healthy subjects during winter. Psychopharmacology 1998;135:319–23.
9. Gloth FM 3rd, Alam W, Hollis B. Vitamin D vs. broad spectrum phototherapy in the treatment of seasonal affective disorder. J Nutr Health Aging 1999; 3:5–7.
10. Martinez B, Kasper S, Ruhrmann S, Moller HJ. Hypericum in the treatment of seasonal affective disorder. J Geriatr Psychiatry Neurol 1994;7:S29–S33.
11. Wheatley D. Hypericum in seasonal affective disorder (SAD). Curr Med Res Opin 1999;15:33–7.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of Garlic and Cholesterol: Everything You Need to Know (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice in Westport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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