Lack of sunlight is a common cause of depression. Around 20% of people experience a drop in their mood in the winter months. Exercise, morning sunlight, therapy, and a lightbox or dawn simulator can help.
Winter depression is caused in part by a change in the body’s biological clock, which sets levels of energy, sleep and appetite. This clock is run by hormones and transmitters in our brain, such as melatonin. Our brains use sunlight to set this clock, and likewise people with winter depression can use artificial sunlight through a lightbox to correct their circadian rhythm.