Abstract P339: Impaired Cardiac Autonomic Modulation in Adolescents: Role of Insomnia Symptoms, Objective Short Sleep Duration and Night-To-Night Sleep Variability

Abstract

Introduction: Impaired cardiac autonomic modulation (CAM), as measured by heart rate variability (HRV), has been associated with increased risk of cardiovascular morbidity. Inadequate sleep has been shown to contribute to impaired CAM, however, it is not clear what sleep problems are independently associated with impaired CAM in adolescents, a population in which insomnia symptoms, short sleep duration and night-to-night sleep variability are highly prevalent. Hypothesis: Insomnia symptoms, objective short sleep duration and high sleep variability are independently associated with worse HRV indices in adolescents. Methods: Data from the Penn State Child Cohort, a randomly-selected sample of 421 adolescents (12-23y) was used. Insomnia symptoms were defined by the presence of self-reported difficulties falling and/or staying asleep on the Pediatric Sleep Questionnaire. All subjects underwent 9-hour, in-lab polysomnography (PSG) and wore an actigraphy (ACT) monitor in the non-dominant wrist for 7 days. Mixed-effect regression models predicting HRV indices included insomnia symptoms, PSG sleep duration and ACT sleep duration and its variability (standard deviation) adjusted for each other as well as for sex, race, age, body mass index, and apnea/hypopnea index. Results: Shorter PSG sleep duration and higher ACT sleep variability were independently associated with decreased parasympathetic and increased sympathetic nervous activity [e.g., SDNN: 2.05±0.70, p<0.01 and -4.50±1.14, p<0.01 and Log-HF: 0.10±0.03, p<0.0 and -0.10±0.05, p=0.05, respectively], while ACT sleep duration or self-reported insomnia symptoms were not [e.g., SDNN: -0.57±0.84, p=0.49 and 0.90±1.26, p=0.47 and Log-HF: -0.06±0.04, p=0.12 and 0.05±0.06, p=0.37, respectively]. Conclusions: Objective, but not subjective, measures of sleep are associated with impaired CAM in adolescents. Interestingly, short PSG sleep duration and high ACT sleep variability are independently associated with impaired CAM, which indicates that these two objective measures may help identify distinct sleep phenotypes associated with increased cardiovascular risk in adolescents. Future studies should examine whether a more severe type of insomnia symptoms, i.e., chronic insomnia, is associated with impaired CAM in adolescents.