The transition from daylight savings time (summer) to standard time (winter) has recently been associated with an increase in depression. We are entering a period where we are losing the long summer days of sunlight. Until winter solstice, the light will wane. A literature review strongly suggests that waning light availability causes fluctuations in brain serotonin levels, which has been associated with Seasonal Affective Disorder (SAD), or what we commonly call winter blues. In fact, bright light therapy is the least invasive and one of the most researched treatments for SAD. It can induce remission in patients with winter depression.
A further look at the literature shows that rapid tryptophan depletion in the diet can reverse the antidepressant effect of bright light therapy in patients with SAD. Tryptophan depletion studies are a mechanism by which a researcher can lower serotonin content in the brain to study its effects. This underscores the idea that the therapeutic effect of bright light in SAD likely involves serotonin. Light is known to maintain higher serotonin levels, but we are losing the optimal amount of light with the time change looming. Why not approach setting back our clocks by heading off moodiness with a 5-HTP supplement? We can build “inner sunshine” by increasing our serotonin with 5-HTP!
 Hansen BT, Sønderskov KM, Hageman I, et al. (2016). Daylight savings time transitions and the incidence rate of unipolar depressive episodes. Epidemiology. Oct 20. [Epub ahead of print] DOI:10.1097/EDE.0000000000000580
 Neumeister A, Praschak-Rieder N, Besselmann B, et al. (1997). Effects of tryptophan depletion on drug-free patients with seasonal affective disorder during a stable response to bright light therapy. Arch Gen Psychiatry. Feb;54(2):133-8.
 Lam RW, Zis AP, Grewal A, et al. (1996). Effects of rapid tryptophan depletion in patients with seasonal affective disorder in remission after light therapy. Arch Gen Psychiatry. 1996 Jan;53(1):41-4.