0635 Associations Between Ambient Light Exposure and Development of Depressive Symptoms in Women at Risk for Postpartum Depression

Abstract

Abstract Introduction There is increasing recognition that ambient light exposure plays a critical role in daytime functioning, including mood regulation. In this analysis, we examined associations between 24-hour light exposure patterns and mood in women at risk of developing postpartum depression. Methods Perinatal women ages 18-40 with a history of major depressive disorder or bipolar disorder who did not meet criteria for depression at study enrollment during 3rd trimester wore wrist actigraphs that recorded ambient light levels for one week at 3rd trimester (~33 weeks’ gestation) and again during postpartum weeks 2, 6, and 16. Depressive symptoms were assessed with the Hamilton Depression Rating Scale (HAM-D-17) at the end of each recording week. To summarize the light data, we calculated the arithmetic mean of the log-light levels in twenty-four 60-minute bins across each day and then aggregated each hour across each recording week. We used nonlinear model fitting (cosinor) to calculate area under the curve (AUC) and compared 24-hour and morning (8:00 am to 12:00 pm) light exposure patterns between women with elevated depression symptoms at week 16 (HAM-D-17 > 7) and women with low depression symptoms at study entry and week 16 (HAM-D-17 <=7) using Mann-Whitney U-tests. Results Compared with women who did not become depressed (n=15), those who ultimately developed depression (n=8) had significantly lower morning light exposure at 3rd trimester and at postpartum week 6, but not at postpartum week 16. Effect sizes were moderate at 3rd trimester (eta-squared=0.30) and small at Week 6 (eta squared=0.24). There were no significant differences in the overall 24-hour AUC of light exposure between participants who developed significant depressive symptoms at postpartum week 16 and non-depressed women at any time point [3rd trimester: p=0.35; postpartum week 6: p=0.92; postpartum week 16: p=0.35]. Conclusion In this sample of perinatal women at risk for postpartum depression, new mothers who developed clinically-significant depressive symptoms at postpartum week 16 had lower levels of morning light exposure during 3rd trimester and at 6 weeks postpartum. Lower peripartum morning light exposure may predict the development of postpartum depression. Support (if any) MH086689 to KMS