SAD seasonal affective disorder

by Re-Timer on 16 Jan 2014

SAD seasonal affective disorder

SAD (seasonal affective disorder) is best known as a condition experienced in cooler climates during the winter months. However, SAD is also experienced  throughout summer by some people. The prevalence rate of SAD drops from 14% in the winter to 4% in summer. SAD is also known as Winter Blues.

SAD or seasonal affective disorder can be alleviated with the use of bright light therapy. Leading researchers have discovered that issues resulting from insufficient exposure to light are best treated with shorter wavelengths of light in the spectrum of 470nm to 500nm which is visibly blue or green in appearance.

These results have been produced and re-produced in various peer-reviewed, placebo controlled studies. The shorter wavelength’s of light are more effective in suppressing the brain’s production of a hormone called melatonin. Effective suppression of melatonin during the day is required to properly entrain the body’s 24-hour sleep-wake pattern. Researchers believe that insufficient light is the cause of both SAD and many advance and delayed rhythm, sleep problems.

One research study found that green light was superior to red light in the treatment of SAD seasonal affective disorder. The study also found the results using green light were similar to broad spectrum white light, but only when sufficient green light was present in this spectrum.

To ensure you purchase a light device which will adequately regulate your sleep-wake cycle and alleviate SAD seasonal affective disorder symptoms, either purchase a light device with visibility green light emitting from it, or purchase a white light and ask your retailer whether it is enriched with green light.

Further information can be found here: