0209 Cardiovascular Measures Display Robust Phenotypic Stability to Total Sleep Deprivation Across Long-Duration Intervals

Abstract

Abstract Introduction For the first time, we determined whether individual differences in cardiovascular (CV) measures are observed in response to total sleep deprivation as well as the stability of such responses across 4-month and 8-month long-duration studies. Methods We conducted a five-day experiment twice (at months 2 and 4) in a 4-month study (N=6 healthy adults; 3 females), and a similar five-day experiment three times (at months 2, 4, and 8) in an 8-month study (N=5 healthy adults; 2 females). During these repeated experiments, CV measures were collected via echocardiography or blood pressure monitor [systolic blood pressure (SBP)] at three assessment time points: 1) after two baseline 8h time in bed (TIB) nights (BL); 2) after a night of total sleep deprivation (TSD); and 3) after two recovery nights of 8-10h TIB (REC). Seated SBP, stroke volume (SV), heart rate (HR), cardiac index (CI), left ventricular ejection time (LVET), and systemic vascular resistance index (SVRI) were collected. Data did not significantly differ between the two studies and therefore were pooled together for analysis (N=11). Intraclass correlation coefficients (ICCs) assessed the stability of CV measures during TSD. Spearman’s rho assessed the relative rank of individuals’ averaged TSD-TSD responses across CV measures. Results TSD ICCs across months 2 and 4 were substantial to almost perfect for all CV measures (0.755-0.962). In the 8-month sample subset, TSD ICCs were moderate to almost perfect across 2, 4, and 8 months for all CV measures (0.643-0.944). Individuals also exhibited significant consistency of responses within CV measures: SV was positively correlated with LVET (ρ=0.791, P=0.004), HR was negatively correlated with LVET (ρ=-0.627, P=0.039) and CI was negatively correlated with SVRI (ρ=-0.936, P< 0.001). Conclusion Vulnerability to repeated TSD exposures showed trait-like stability in CV measures across months 2, 4, and 8, with significant consistency of responses within CV measures. For the first time, we demonstrate robust phenotypic stability of cardiovascular measures during total sleep deprivation across 2-month, 4-month and 8-month time points in long-duration studies. Our results herald the use of biomarkers and countermeasures for prediction and mitigation of this critical vulnerability. Support (if any) NASA grants NNX14AN49G and 80NSSC20K0243 (NG)