What question did this study set out to answer?

To compare heart rate variability indices among patients with narcolepsy type 1, type 2, idiopathic hypersomnia, and controls.

May 10, 2026

0714 Heart Rate Variability Across Central Disorders of Hypersomnolence

Key Points

To compare heart rate variability indices among patients with narcolepsy type 1, type 2, idiopathic hypersomnia, and controls.
Included adults with NT1, NT2, and IH diagnosed per ICSD-3-TR between 2012-2024.
Participants underwent polysomnography (PSG) followed by multiple sleep latency testing (MSLT).
Heart rate variability indices were derived from ECG during PSG.
No significant differences in SDNN and RMSSD among NT1, NT2, IH, and controls were observed (p=0.39 and p=0.52, respectively).
Indices tended to be lower in idiopathic hypersomnia but not statistically significant, suggesting limited usefulness in detecting autonomic dysfunction.

Abstract

Abstract Introduction Central disorders of hypersomnolence (CDH), including narcolepsy type 1 (NT1), narcolepsy type 2 (NT2), and idiopathic hypersomnia (IH), are associated with autonomic abnormalities. Animal studies show that orexin loss reduces sympathetic tone. However, clinical studies assessing autonomic function, including heart rate variability (HRV), in NT remain limited and inconsistent. Autonomic impairment is also reported in IH, but HRV is evaluated in only one study revealing increased parasympathetic tone during wake and sleep. The objective was to compare HRV in patients with NT1, NT2, IH and controls Methods Adults with NT1, NT2, IH according to ICSD-3-TR who underwent PSG followed by MSLT (PSG/MSLT) at Cleveland Clinic from 2012-2024 were included. Controls were individuals who completed PSG/MSLT in the same period with no CDH, with habitual sleep time 7hours and mean sleep latency ≥12 minutes on MSLT. All participants had AHI 10, PLMI 10, and were free of medications affecting HRV. HRV indices- standard deviation of NN intervals (SDNN) and root mean square of successive differences (RMSSD) were derived from the ECG signal during PSG. Results A total of 213 adults were analyzed (18 NT1, 39 NT2, 103 IH, and 53 controls), with a predominance of females in all diagnostic groups (77.8% NT1, 69.2% NT2, 78.4% IH, and 71.7% controls). Mean age differed modestly across groups (overall 33.5±12.6 years; p=0.032). No significant difference in overall, NREM sleep, REM sleep, light sleep, deep sleep SDNN and RMSSD among NT1, NT2, IH, and control was observed. Overall SDNN was 68.3ms 52.9, 78.4 in NT1, 64.4ms 50.5, 100.9 in NT2, 61.5ms 46.0, 90.5 in IH, and 68.0ms 57.3, 90.4 in control (p-value 0.39). Overall RMSSD was 74.0ms 47.3, 85.6 in NT1, 67.0ms 49.4, 126.6 in NT2, 57.8ms 42.0, 103.9 in IH, and 66.3ms 53.9, 95.9 in control (p-value 0.52). Conclusion SDNN and RMSSD did not differ significantly among CDH subtypes or controls across sleep stages. Although these indices tended to be consistently lower in IH, differences were not statistically significant, suggesting limited utility of conventional HRV measures in detecting autonomic dysfunction in CDH. Support (if any) NIH grant 1R21HL170206-01

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