Light Therapy for Seasonal Affective Disorder and Winter Blues
Seasonal Affective Disorder (SAD) is a mood disorder that an estimated 7% of the UK population suffer from. A further 17% suffer from its milder form, Winter Blues. It is a form of depression brought about by the reduced intensity and length of sunlight in the Winter months, particularly during December, January and February.
What causes SAD?
Seasonal Affective Disorder, and its milder form, Winter Blues, are caused by the reduced amount of sunlight during the winter. Your body relies on sunlight to give it cues for when it should be alert, and when it should be rested. The lack of sunlight can trick your body into thinking it should constantly be in a state of rest or sleep, causing reduced alertness, energy and happiness.
During winter months, many people are exposed to less than an hour's direct sunlight. When leaving for work it is dark, and it is then dark when leaving too. Most indoor environments are not sufficiently bright for the body to acknowledge it as being daytime – the body needs brightness of 2,500 lux, while even a well-lit office will only provide 500 lux. As a result your body never truly “wakes up”.
How is it treated?
Light therapy is successful in treating 85% of people with SAD. It works by exposing patients to light in excess of 2,500 lux, making their bodies accept that it is daytime and now needs to be alert and active.
The body begins to produce serotonin, a chemical linked with a feeling of well-being. Its production is triggered by the body receiving sunlight. Similarly, sunlight also tells the body to stop producing melatonin, a hormone that prepares the body for sleep. Without this sunlight trigger, the body does not produce serotonin, and instead continues to produce melatonin - making you feel tired and depressed. Light therapy replicates sunlight - giving your body the trigger it needs to function correctly.