0682 Circadian Rest/activity Rhythms Are Associated with Daytime Symptoms Among Older Adults with Insomnia

Abstract Introduction We investigated the association between circadian rest/activity rhythms (RARs) and daytime insomnia symptoms among older adults with insomnia. We hypothesized that: 1) RARs differ between older adults with insomnia and healthy sleepers; and 2) among older adults with insomnia, RARs are associated with daytime insomnia symptoms. Methods Older adults with insomnia (n=30) and healthy sleepers (n=33) were recruited from a tertiary academic medical center. Nonparametric RARs were derived from actigraphy data over 14 days: relative amplitude (RA), interdaily stability (IS), intradaily variability (IV), maximum ten-hour activity (M10) and minimum five-hour activity (L5). Secondary parametric RARs included amplitude, acrophase, and midline statistics of rhythm (MESOR). Daytime function was evaluated via the Daytime Insomnia Symptoms Scale (administered via smartphone 4x/day, i.e., 56 assessments per participant) and validated research questionnaires (administered once). Between-groups differences (insomnia vs healthy sleep) were evaluated using t-tests. Among individuals with insomnia, a series of 104 linear regression models examined the association between RARs and daytime symptoms. The Benjamini-Hochberg procedure for correcting false discovery rate (BH-FDR) was used to correct for multiple comparisons. Results Relative to healthy sleepers, older adults with insomnia demonstrated significantly lower RA (p=0.028,t=-2.28) and significantly higher L5 (p=0.018,t=2.48). Among older adults with insomnia, IS was positively associated with positive mood (p=0.013, t =2.67) and negatively associated with pre-sleep somatic arousal (p=0.01, t=-3.06). IV was negatively associated with DISS subscales including Alert Cognition (p=0.001, t=-3.64) and Positive Mood (p< 0.001, t=-4.15) and positively associated with Negative Mood (p< 0.001, t=4.74), and Sleepiness/fatigue (p=0.005, t=3.11), as well as validated questionnaires measuring depression (p=0.02, t=2.47), negative mood (p< 0.01, t=3.43), and pre-sleep somatic arousal (p=0.01, t=3.77). M10 was negatively associated with depression (p< 0.0,1 t=-3.29) and anxiety (p=0.01 t=-2.9). Of parametric RARs, amplitude was negatively associated with negative mood (p=0.005, t=-3.08) and depression (p=0.01, t=-2.75), and positively associated with positive mood (p=0.010, t=2.77). MESOR was negatively associated with depression (p=0.02, t=-2.48) and anxiety (p=0.01, t=-2.81). Conclusion Among older adults with insomnia, RARs were associated with daytime insomnia symptoms. Future research should examine how to optimize circadian components of therapeutic interventions in insomnia clinical care. Support (if any) Merck Investigator Studies Program (#59170).