SLEEP IN FALL WINTER SEASONAL AFFECTIVE-DISORDER - EFFECTS OF LIGHT AND CHANGING SEASONS

Disturbances of sleep are a hallmark of seasonal affective disorders ( SAD), as they are of other mood disorders. Fall/winter SAD patients mo st often report hypersomnia. Among responses of 293 SAD patients on a symptom questionnaire, complaints of winter hypersomnia (80%) greatly exceeded insomnia (10%), hypersomnia plus insomnia (5%), or no sleep d ifficulty (5%). Increased sleep length in fall/winter is not unique to SAD. Among 1571 individuals across four latitudes surveyed at random from the general population, winter sleep increases of less-than-or-eq ual-to 2 hr/day relative to summer were reported by nearly half. Howev er, hypersomnia had a low correlation (r = 0.29) with the total number of other SAD symptoms that were reported in this sample. Ten SAD pati ents kept daily sleep logs across 1 yr that showed increases in fall a nd winter (sleeping most in October; least in May) whose maximum avera ged 2.7 hr per day more weekend sleep than in spring and summer. These winter increases might have been somewhat attenuated since most recei ved light therapy during part of the winter. Nocturnal EEG recordings of depressed SAD patients in winter showed decreased sleep efficiency, decreased delta sleep percentage, and increased REM density (but norm al REM latency) in comparison with recordings: (1) from themselves in summer; (2) from themselves after greater-than-or-equal-to 9 days of l ight therapy; or (3) from age- and gender-matched healthy controls. Th us, the extent of fall/winter oversleeping recorded by our SAD patient s did not differ dramatically from that reported by the general popula tion, but sleep complaints of our SAD patients have been accompanied b y features of sleep architecture that are different from healthy contr ols and are reversed by summer or by bright-light therapy.