0623 Effects of bright light therapy on objective and subjective sleep in patients with non-seasonal depression and eveningness

Abstract Introduction This study reported the effect of bright light therapy with gradual advanced timing on the sleep parametersin patients with major depressive disorder (MDD) and eveningness. Methods A total of 93 adults were randomized to receive either 10,000 lux bright light therapy (BLT group) or 50lux dim red light therapy (placebo group) for a total of 5 weeks. Timings of both treatments were initiated at their habitual wake time and was advanced gradually each week. Sleep diary data were collected weekly. Actigraphic data were collected at the baseline and during the last week of the 5-week treatment. Sleep parameters including time in bed (TIB), sleep onset latency (SOL), wake after sleep onset (WASO), total sleep time (TST) and sleep efficiency (SE) were extracted. Concordance of the sleep diary and actigraphy sleep parameters were assessed by Pearson’s correlation with p-value adjusted for multiple comparisons. The changes of sleep parameters between the two groups were assessed by linear mixed model. Results Significant correlations between sleep diary and actigraphy were found for WASO (r=0.35, p = 0.01) and TST (r=0.40, p=0.01), but no correlation was found for TIB, SOL and SE. A greater advance in the diary-based light-out time (group*time p=0.03, 15 vs 32min) and rise time (group*time p=0.04, 38 vs 53min) was found in the BLT group compared to placebo group, while dairy-based WASO, TST and SE comparably improved with time in both groups. However, there were no significant difference between the two groups in all of the actigraphic parameters after treatment. Conclusion Five-week of either type of light therapy with gradual advance in timing improved subjective WASO, TST and SE, while BLT led to a greater advance in the light-out time and rise time when compared to the placebo group. These changes were not captured by the actigraphic measurements. The discrepancies between subjective and objective sleep parameters suggested the need to consider incorporating multiple measures when assessing sleep in patients with depression and eveningness. Support (if any) This project was supported by the Health and Medical Research Fund, The Government of Hong Kong SAR (Ref 12131131).