0041 Greater Depression Severity Is Associated with Later Circadian Eating Time in Those with Seasonal Depression

Abstract Introduction Circadian misalignment is a transdiagnostic feature of depression and metabolic dysfunction. Timing of food intake can alter peripheral clocks creating internal circadian misalignment. The atypical symptoms of depression seen in seasonal affective disorder (SAD), such as over eating, can exacerbate circadian misalignment by delaying or prolonging the eating window. Greater atypical depression severity may have increased risk for metabolic dysfunction, possibly through pronounced misalignment. The current study tested the effects of depression severity on circadian eating behaviors in SAD. We hypothesized that greater depression severity would predict later circadian eating time and longer eating windows. Methods Participants age 18-65 included SAD (n=33), subsyndromal SAD (S-SAD; n=16), and controls (n=41; total N=90). Depression severity and circadian phase (dim light melatonin onset; DLMO) were measured in winter. Electronic diaries collected the timing of first and last meal to determine the daily eating window. Circadian eating time was calculated as the difference between DLMO and the midpoint between the first eating observation and last eating observation. Multi-level modeling with a random intercept of participant was used to examine the impact of depression severity on daily measures of circadian eating time and eating window length. Covariates included age, gender, weekday/weeknight, and number of diary assessments. Results Participants reported mealtimes over 4 to 19 days (M=8.88, SD=3.62). On average, eating midpoint occurred 7.24 hours before DLMO (SD=1.90). Average eating window length was 9.01 hours (SD=3.41). Greater depression severity was associated with later circadian eating time (i.e., shorter interval between eating midpoint and DLMO; b=-0.03, SE=0.01, p=0.03). Depression severity was not associated with eating window length (b=-0.02, SE=0.02, p=0.36). Conclusion In a sample of individuals with SAD greater depression severity was associated with later circadian eating time, suggesting that people with greater depression are eating closer to their biological night. Longitudinal data are needed to determine if mealtimes, circadian phase, or depression initiate a maladaptive cycle. In contrast to our hypothesis, no relationship was found between depression severity and length of eating window. Length of eating window is independent of timing of eating window, suggesting that timing may be more important than total hours of food consumption in depression. Support (if any)