Defining Autonomic Norms During Sleep: A Comparison of Healthy and InsomniaPopulations Using Polysomnography
Angeliki Pollatou, Ph.D., Soroosh Solhjoo, Ph.D., Caddie Motoni, B.S., Bradford Clemens, B.S., Elizabeth Metzger, M.S.P.H., J. Kent Werner, Jr., M.D., Ph.D.
Background: Autonomic dysregulation is increasingly recognized as a key factor in sleep disorders, yet normative data for autonomic function during sleep remain limited. Understanding how autonomic parameters vary across sleep stages in healthy individuals and those with insomnia can provide insight into sleep-related physiological processes. This study aims to define autonomic norms in a healthy population and compare them with individuals experiencing insomnia.
Methods: For our preliminary studies, we analyzed retrospective polysomnography data from medical records, identifying healthy participants and individuals with insomnia. Electrocardiograms were used to assess autonomic function across sleep stages, focusing on heart rate, normal-to-normal (NN) interval, heart rate variability measures (SDNN, RMSSD, VLFPow, LFPow, HFPow), and QT interval variability index. Comparisons were conducted across sleep stages, particularly wakefulness after sleep onset (wake) and rapid eye movement sleep (REM) when autonomic differences are most pronounced. Data analysis is ongoing, with a target of 50 participants per group for robust statistical comparisons.
Results: Normative autonomic indices were established in healthy participants (N=7). Individuals with insomnia (N=3) exhibited higher heart rates and shorter NN intervals suggesting increased sympathetic activation. During wake, patients with insomnia had a higher heart rate (73.31±9.70 bpm vs 59.43±9.47 bpm, P<0.001) and shorter NN intervals (833.46±114.88 ms vs 1033.95±155.92 ms, P<0.001). Similar patterns were observed in REM sleep (heart rate: 63.38±8.59 bpm vs 59.39±7.58 bpm, P<0.001; NN interval: 962.67±119.73 ms vs 1027.20±133.91 ms, P<0.001). Further analysis will determine whether these trends persist across other sleep stages and electrophysiologic indices.
Conclusions: This study establishes baseline autonomic norms and highlights key differences in insomnia, where individuals show heightened sympathetic activity and reduced parasympathetic modulation, particularly during wake and REM sleep. Identifying these autonomic patterns may aid in developing targeted interventions for insomnia and related sleep disorders. With data collection in progress, future analyses will determine whether these trends remain significant with a larger sample size (N=50 per group) and across different insomnia phenotypes.