Effective antidepressants are fluoxetine, sertraline, or paroxetine. Both fluoxetine and light therapy are 67% effective in treating SAD, according to direct head-to-head trials conducted during the 2006 Can-SAD study. Subjects using the light therapy protocol showed earlier clinical improvement, generally within one week of beginning the clinical treatment. Bupropion extended-release has been shown to prevent SAD for one in four people, but has not been compared directly to other preventive options in trials. In a 2021 updated Cochrane review of second-generation antidepressant medications for the treatment of SAD, a definitive conclusion could not be drawn, due to lack of evidence, and the need for larger randomized controlled trials.Modafinil may be an effective and well-tolerated treatment in patients with seasonal affective disorder/winter depression.Another explanation is that vitamin D levels are too low when people do not get enough Ultraviolet-B on their skin. An alternative to using bright lights is to take vitamin D supplements. However, studies did not show a link between vitamin D levels and depressive symptoms in elderly Chinese, nor among elderly British women given only 800IU when 6,000IU is needed. 5-HTP (an amino acid that helps to produce serotonin, and is often used to help those with depression) has also been suggested as a supplement that may help treat the symptoms of SAD, by lifting mood, and regulating sleep schedule for those with the condition.
The survey also shows women are more likely to be affected by SAD than men. An estimated 3% of the population in the Netherlands experience winter SAD. See also
Diurnal Cycle
Seasonal effects on suicide rates
Seasonal Pattern Assessment Questionnaire
Vitamin D deficiency

References
External links
Seasonal Affective Disorder at Curlie
USA National Institute of Mental Health webpages https://www.nimh.nih.gov/health/topics/seasonal-affective-disorder/index.shtml