0419 Characterization of Sleep Quality in Patients with Idiopathic Hypersomnia using Cardiopulmonary Coupling

Abstract

Abstract Introduction Idiopathic Hypersomnia (IH) is characterized clinically by excessive daytime sleepiness, prolonged or unrefreshing sleep, and sleep inertia. The ICSD-3 classifies IH as having expected proportions of NREM and REM sleep, normal REM latency and relatively high sleep efficiency. However, there is limited granular data on sleep quality in these patients and whether this disease state comprises of patients with a homogenous spectrum of sleep quality. The aim of this study is to describe the sleep quality in patients with IH using the ECG derived sleep spectrogram. Methods This is a single center cross sectional study where we identified 37 consecutive extended sleep studies for patients with 10 or more hours of total sleep time (TST). The sleep spectrogram is an ECG or plethysmography based system which evaluates sleep stability based on the principle of autonomic and respiratory oscillations (cardiopulmonary coupling). High frequency coupling (HFC) is associated with stable NREM sleep. Sleep quality index (SQI) is strongly weighted by HFC. We a priori decided to divide this population into 2 groups based on SQI ≥55 (there is published supportive data for using this threshold in adults) and compare them using T-test. Multivariable logistic regression was performed adjusting for age, sex, TST and apnea-hypopnea index-3% (AHI) <10 to assess predictors of high or low SQI which was discovered. Results The mean age for the cohort was 35.4 years (SD 16.2), of which 30 (81%) were females. Mean TST was 660 minutes (SD 16.2) with mean sleep efficiency of 86% (SD 9) and mean SQI of 59% (SD 19.1). Mean AHI was 10.4 (SD 12.3). Stratifying the cohort based on SQI gave us 2 distinct groups with mean SQI of 71.5 (SD 9.3) in group with SQI≥55 and mean SQI of 38.5 (SD 11.6) in group with SQI <55 [p-value <0.001]. In a logistic regression analysis, the SQI was not predicted by AHI <10, age, gender or total sleep time. Conclusion Based on our cohort, at least two clusters were identified in IH. We anticipate that the findings here will lead to further insights in IH physiology and phenotypes. Support (If Any)