0159 Age as a Moderator for the Relationship Between Exercise Before Bed and Daytime Sleepiness

Introduction It is axiomatic that sleep and exercise are important for good health. However, in the Sleep Hygiene Index (SHI), we suggest exercise within one hour of bedtime is a sleep-related behavior to avoid. More recently, in a systematic review no support was found for evening exercise negatively affecting sleep. Here, we examine age as a moderator for the relationship between sleep and sleep outcomes to reconcile these findings. Methods Data were gathered from 10 previous studies from our laboratory administering the SHI and at least one sleepiness measure (Epworth Sleepiness Scale (ESS) and/or the Pittsburgh Sleep Quality Index (PSQI). Participants included primarily college students but also non-college student populations (faculty/staff, alumni, parents, and local community members). This sample included 1668 18-23 year-olds, 219 24-39 year-olds, and 199 40-85 year-olds. Participation was incentivized with bonus points or opportunities to win gift cards. Focus here was on the SHI exercise question (“I exercise to the point of sweating within 1 h of going to bed”) answered on a 5-point scale (1=never to 5=always). Results Intense exercise within one hour of bed was not common (18-23 year-olds, M=1.58; 24-39 year-olds, M=1.48; 40-85 year-olds, M=1.36). The correlation between exercise and sleepiness measures was quite small (ESS, r(1570)=0.094; PSQI-Global, r(1526)=0.027, and PSQI-Daytime Dysfunction, r(1557)=-0.045). However, the relationship between exercise and sleepiness was significantly moderated by age (b=.935, t(1462)=3.55, p<.001). Although there was no significant relationship for the youngest participants between exercise and sleepiness, a significant small (β=0.09) positive relationship for the middle age group (b=.412, z=3.66, p<.001) and a small to medium (β=0.19) positive relationship for the oldest participants (b=.819, z=5.02, p<.001) existed. Conclusion These findings suggest age moderates the relationship between exercise close to bed and sleep outcomes. Although resiliency may protect the young, middle aged and older adults are likely to be vulnerable to pre-sleep exercise. We found although exercise close to bed did not predict sleepiness in younger participants, for older participants the negative effect of exercise close to bed was apparent and increased with age. Clinically, age may be an important variable to consider when advising against exercise before bed. Support (if any)