O045 Sleep Duration is Associated with Young Adult's Heart Rate Variability Response to Stress

Abstract Introduction Young adulthood is a critical developmental period typified by heightened exposure to stress, and a tendency towards insufficient sleep. The relationship between sleep loss and stress may have lifelong health consequences. Currently, our understanding of this relationship in young adults is limited. Heart rate variability (HRV) is an important indicator of balance in the autonomic nervous system. We examined the association between sleep duration and HRV in response to cognitive stressors. Methods Seventy-six young adults (M=20.6±1.9, 72.4% female) who self-identified as short sleepers were recruited. Habitual sleep duration was monitored with actigraphy for two weeks. Participants subsequently underwent an in-lab experiment where their HRV was recorded during baseline, and during a cognitive stress condition involving the completion of computerised cognitive stress tasks. Participants also reported their habitual stress levels and sleep quality. Results Actigraphy assessment revealed that participants slept within the recommended sleep durations (M=7.8±0.7). The participants reported high habitual stress but normal sleep quality. Our moderation analysis indicates that shorter sleep duration was associated with elevated HRV during the cognitively demanding tasks. Conclusions Our findings demonstrate an association between sleep duration and HRV in the context of a cognitive stressor, indicating that sleep and stress are related in young adults. An unexpected negative relationship between sleep duration and HRV during the cognitively demanding tasks suggests complexity in this relationship; however, we should still look to reduce stress and improve sleep where we can in young adults. This association may be better understood via direct manipulation of sleep duration.