1110 Change in Subjective and Objective Sleep Measures During Cognitive-Behavioral Therapy and Light Therapy for Winter Depression

Introduction Winter seasonal affective disorder (SAD) is characterized by a regular pattern of major depressive episodes that recur in fall/winter and spontaneously remit in spring/summer. Some SAD patients show circadian rhythm disturbances, with their circadian phase occurring later (phase delayed) or, less commonly, earlier (phase advanced) compared to healthy individuals in the winter. Sleep disturbances are common in SAD, including insomnia, hypersomnolence, sleep inertia, and abnormal sleep architecture. In this study, we compared pre- to post-treatment changes in subjective and objective sleep measures during a randomized clinical trial of group cognitive-behavioral therapy for SAD (CBT-SAD) vs. light therapy (LT). We expected larger improvements in sleep measures in LT than in CBT-SAD, given LT’s assumed mechanism is correction of circadian phase. Methods Community adults aged 18+ years with Major Depression Recurrent with Seasonal Pattern (N=141) were randomized to six weeks of CBT-SAD (n=73) or LT (n=68). For one week at pre- and post-treatment, participants wore the ActiGraph GT9X-BT and completed the Pittsburgh Sleep Diary daily. Linear mixed effects models were conducted on these actigraphy- and diary-derived variables: sleep efficiency (SE), total sleep time (TST), and midsleep. Results All Treatment × Time interactions were ns. Significant pre- to post-treatment time effects were found for higher diary-measured SE [F(1, 117) = 18.485, p < .001; 2.4% higher], longer TST as measured with diaries [F(1, 123) = 5.840, p = .017; 11.4 minutes longer] and shorter TST with actigraphy [F(1, 109) = 8.604, p = .004; 10.6 minutes shorter], and earlier actigraphy-measured midsleep [F(1, 110) = 10.214, p = .002; 12.2 minutes earlier]. Conclusion Participants perceived that their sleep continuity (SE) improved over treatment, whereas actigraphy found no meaningful pre- to post-treatment difference. Participants perceived longer sleep duration at post- compared to pre-treatment, whereas actigraphy revealed the opposite pattern. It is possible that participants perceived better sleep because they generally felt better following treatment. Actigraphy-measured sleep timing (midsleep) advanced over both treatments. Support (if any) Grant R01MH112819 (PI: Rohan).