Spring Sunlight Serotonin + Melatonin

According to Thompson, the seasonal changes that bring most of us out of winter apathy may work against those who are coming out of severe depression. "It is a harsh irony that the partial remission which most depression sufferers experience in the spring often provides the boost of energy required for executing a suicide plan," he says. "Spring is a time for new beginnings and new life, yet the juxtaposition between a literally blooming world and the barren inner life of the clinically depressed is often too much for them to bear."

Paradoxically, says Thompson, sunlight-driven changes in levels of the feelgood chemical serotonin may make people more aggressive and, if they are depressed, they could direct that aggression at themselves. The theory gains some support from research by Canadian scientists linking seasonal changes in bright sunlight with more violent suicides.

Other researchers believe that the influence of sunlight on another hormone, melatonin, is to blame. Sunlight inhibits production of melatonin, which is known to influence our behaviour.

//www.theguardian.com/science/2005/may/12/mentalhealth.society