2. Light At Night
Exposure to dim lighting at night, such as that generated by a TV, computer screen or e-reader could lead to symptoms of depression. A study of 516 elderly people found exposure to light at night was significantly associated with higher scores on a geriatric depression scale.
Photosensitive cells in the retina detect light and transmit signals to the circadian clock in the brain that controls the natural sleep-wake cycle. Artificial illumination at night, especially blue and white light, disrupts circadian rhythms and suppresses the release of the hormone melatonin. Too little melatonin can result in mood disorders.