Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .
Side effects of short-term 10,000-lux light therapy.
OBJECTIVE Previous reports of side effects from light therapy were mostly based on administration of 2,500-lux treatments . It has become common practice to use brighter , 10,000-lux exposure when treating seasonal affective disorder . The authors studied side effects produced by short-term 10,000-lux light therapy . METHOD Seventy subjects with seasonal affective disorder who underwent brief 10,000-lux light therapy  were asked to report side effects . RESULTS Of the 70 subjects , 32 ( 45.7 % ) experienced side effects , and nine ( 12.9 % ) reported two or more apiece . Headaches and eye or vision problems were the most common . Almost all were mild , were transient , and did not interfere with treatment . CONCLUSIONS Short-term 10,000-lux light therapy often produces side effects early in treatment . These are not serious or prolonged , however , confirming findings from earlier studies that used dimmer light
Recent systematic review s have shown that  light therapy  is an efficacious and well-tolerated treatment for SAD .
There is also evidence for efficacy of pharmacotherapy to treat and prevent SAD .
SAD is a common condition with significant psychosocial impairment .
BACKGROUND Seasonal affective disorder ( SAD ) consists of recurrent major depressive episodes in the fall/winter with remissions in spring/summer .
RESULTS A careful history is important to make the diagnosis and differentiate SAD from other similar conditions such as subsyndromal SAD and atypical depression .
Seasonal patterns with winter worsening are also recognized in " nonseasonal " depression as well as many other psychiatric conditions , and comorbidity with SAD is common .
The pathophysiology of SAD seems to be heterogeneous as research on circadian , neurotransmitter function and genetic hypotheses have shown discrepant results .
A dual vulnerability model with differential loading on separate seasonal and depression factors has been proposed to explain these findings .