The Chemistry Of SAD (Seasonal Affective Disorder)

sad lights

The chemistry of Seasonal Affective Disorder seems to be directly related to the balance between two important chemicals found in the brain, melatonin and serotonin. Melatonin is the chemical that regulates sleep. It in turn is regulated by light. Within the brain, there direct connections between the retina, where light is received and measured, and the pineal gland, where melatonin is produced. The onset of its production is triggered by darkness, the body’s cue to rest. Once the body’s exposure to light increases, though, melatonin production decreases and the body converts its energy to serotonin production.

Serotonin is one of the chemicals responsible for the brain’s control over mood and appetite. High levels have been linked to positive feelings, relaxation and the ability to focus. When the brain’s production of melatonin switches over to serotonin it tells the body that it is time to be awake and alert.

Recent research suggests that serotonin levels are the key to SAD. While melatonin levels seem to remain the same in both those who experience SAD and those who don’t, serotonin levels have been show to be significantly lower in seasonally depressed patients. Scientists show that the proteins responsible for clearing the brain of excess serotonin are extremely active during periods of darkness, depressing serotonin levels to aid sleep. When the body and the brain are not exposed to enough light, as sometimes occurs during the winter months, serotonin levels stay low during the day as well.