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 .
Modafinil treatment in patients with seasonal affective disorder/winter depression: an open-label pilot study.
BACKGROUND Hypersomnia is a cardinal symptom of seasonal affective disorder/winter depression . This open-label pilot study assessed modafinil , a novel wake-promoting agent , as treatment for seasonal affective disorder/winter depression . METHODS Total daily modafinil dose was 100 mg ( all patients week 1 ) , and 100 mg or 200 mg split dose ( weeks 2 - 8 ) . Efficacy assessment s ( weeks 1 , 2 , 5 , and 8) included the Structured Interview Guide for the Hamilton Depression ( HAM-D ) Rating Scale , Seasonal Affective Disorder Version ( SIGH-SAD ) , Montgomery-Asberg Depression Rating Scale ( MADRS ) , Clinical Global Impression of Change ( CGI-C ) , Fatigue Severity Scale ( FSS ) , and Epworth Sleepiness Scale ( ESS ) . RESULTS Thirteen patients ( 11 women ; mean age , 41 years ) were enrolled , 12 were evaluable for efficacy ( 100 mg dose , five patients ; 200 mg dose , seven patients ) , and nine completed treatment . Modafinil significantly improved winter depression as shown by reductions from baseline in mean SIGH-SAD at week 1 ( P<0.01 ) through week 8 ( P<0.001 weeks 2 - 8 ) and MADRS total scores from week 2 through week 8 ( P<0.01 for all ) . At week 8 , mean SIGH-SAD total score was 17.1 ( versus 37.2 at baseline , P<0.001 ) , and mean MADRS total score was 13.3 ( versus 26.9 at baseline , P<0.01 ) . Modafinil significantly improved overall clinical condition at all time points ( P<0.001 ) . The response rate was 67 % on the SIGH-SAD ( 29 item ) , HAM-D ( 21 item ) , and MADRS , and 100 % on eight atypical SIGH-SAD items . Modafinil significantly reduced fatigue ( FSS ) and improved wakefulness ( ESS ) from weeks 2 through 8 ( P<0.01 ) . Modafinil was well tolerated . LIMITATIONS This was an open-label , single site study . CONCLUSIONS Modafinil may be an effective and well-tolerated treatment in patients with seasonal affective disorder/winter depression
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 .