0230 Comparing Subjective and Objective Measures of Chronotypes and Their Associations with Age in Older Adults

Abstract Introduction While much is known about the development and variability of chronotype (CT) in young adults, little is known in older adults, whose circadian rhythms tend to advance with aging. We assessed the associations between subjective and objective non-invasive chronotype markers, and their associations with demographics in older adults. Methods In an observational study of 60 community-living adults aged ≥60 years with self-reported sleep complaints, participants completed a Morningness-Eveningness Questionnaire (reduced version; rMEQ) and seven days of actigraphy. We dichotomized rMEQ into morning (>17) and other-CT(≤17). Seven-day average sleep midpoint, the midpoint between sleep onset and sleep offset, was measured by actigraphy. Seven-day average peak time in activity during the day was calculated using cosinor analysis of activity counts from actigraphy. Two-sample T-tests and Chi-square tests compared demographic factors (age, gender, race, education) and objective chronotype markers (sleep midpoint, peak time) between dichotomized CT groups (Morning-CT vs Other-CT). Pearson correlation coefficients examined the associations between the continuous rMEQ score and objective chronotype markers, and their associations with age. Results The mean age was 74±6.4 years [range: 60-90], 65% were women and 33.3% were minority race. Morning-CT (54%) and Other-CT (46%) had significantly different sleep midpoints (2:43 AM vs 3:20 AM, p=0.01) and different peak times (2:00 PM vs 3:00 PM, p=0.006). No significant differences were found in demographics between Morning-CT and Other-CT. Higher rMEQ score was significantly associated with earlier sleep midpoint (r=-0.52, p< 0.001) and earlier peak time (r=-0.51, p< 0.001). Advanced age was associated with earlier sleep midpoint (r=-0.46, p=0.0003), earlier peak time(p=-0.46, p=0.0003), and higher rMEQ score (r=0.22, p=0.09). Conclusion Among community-living older adults with sleep disturbances, we observed moderate correlations between subjective and objective chronotype markers. The rMEQ score significantly differentiated people with distinct objective chronotype markers, demonstrating the potential validity of rMEQ as a feasible marker for chronotype. Future studies with larger sample sizes should validate our findings, and could investigate whether subjective or objective chronotype markers have stronger associations with adverse outcomes. Support (if any) NIA (K76AG0749505, R03AG073991, P30AG021342)