What is seasonal affective disorder (SAD)?
Seasonal affective disorder (SAD), also known as winter depression, winter blues, summer depression or seasonal depression, is a mood disorder subset in which people who have normal mental health throughout most of the year experience depressive symptoms at the same time each year, most commonly in the winter.
Various proximate causes have been proposed. One possibility is that SAD is related to a lack of serotonin could play a role in SAD
Photoperiod-related alterations of the duration of melatonin secretion may affect the seasonal mood cycles of SAD. This suggests that light therapy may be an effective treatment for SAD. Light therapy uses a lightbox which emits far more lumens than a customary incandescent lamp. Bright white “full spectrum” light at 10,000 lux, blue light at a wavelength of 480 nm at 2500 lux or green light at a wavelength of 500 nm at 350 lux are used, with the first-mentioned historically preferred.
Bright light therapy is effective with the patient sitting a prescribed distance, commonly 30–60 cm, in front of the box with her/his eyes open but not staring at the light source for 30–60 minutes. A study published in May 2010 suggests that the blue light often used for SAD treatment should perhaps be replaced by green or white illumination. Discovering the best schedule is essential. One study has shown that up to 69% of patients find lightbox treatment inconvenient and as many as 19% stop use because of this.
Dawn simulation has also proven to be effective, there is an 83% better response when compared to other bright light therapy. When compared in a study to negative air ionization, bright light was shown to be 57% effective vs. dawn simulation 50%. Patients using light therapy can experience improvement during the first week, but increased results are evident when continued throughout several weeks. Most studies have found it effective without use year round but rather as a seasonal treatment lasting for several weeks until frequent light exposure is naturally obtained.