Nocturnal sleep stage stability features in unexplained hypersomnolence.

STUDY

OBJECTIVES

Evaluate nocturnal polysomnography sleep stage stability features in an adult, sample of clinical patients with hypersomnolence disorder (HD) against healthy sleeper controls (HSCs). Explore differences in sleep stage stability features across HD who displayed objective criteria for idiopathic hypersomnia (IH) (HD/IH+) and those who did not (HD/IH-).

METHODS

Sixty unmedicated clinical patients with HD (average age = 28.6 ± 8.6 years; percentage female = 78.3%) and 29 HSCs underwent ad libitum nocturnal polysomnography and daytime Multiple Sleep Latency Tests. Sleep stage stability features included number of stage bouts, median stage bout duration, number of transitions between stages, and survival analysis of stage bouts. Regression and Cox proportional hazards models compared HD against HSC. Analysis of covariance, log-rank tests, and pairwise comparisons explored differences between HSC, HD/IH+ (n = 14), and HD/IH-. All analyses accounted for age, sex, body mass index, and depressive symptom severity.

RESULTS

HD displayed longer non-rapid eye movement (NREM) stage 2 sleep bouts (P = .02) and increased survival of NREM stage 2 sleep (P < .0001) and rapid eye movement (REM) (P < .0001) bouts, relative to HSC, with fewer NREM stage 3 sleep bouts (P = .02) that were comparable in duration and survival. Many phenotypic similarities were observed between HD/IH+ and HD/IH-, though HD/IH+ displayed significantly increased NREM stage 2 sleep survival (P = .03), longer sleep duration (P = .004), and greater sleep continuity (P = .003).

CONCLUSIONS

Our findings demonstrate enhanced NREM stage 2 sleep and REM stability in adult clinical patients with unexplained hypersomnolence. Follow-up studies are necessary to determine the role of distinct sleep stage stability features as valid, reliable and specific signatures of unexplained hypersomnolence. These results may also be useful for future nosological frameworks that consider unexplained hypersomnolence along a continuum of severity that includes both HD and IH.

CITATION: Cook JD, Rumble ME, Vascan AM, et al. Nocturnal sleep stage stability features in unexplained hypersomnolence. J Clin Sleep Med. 2025;21(11): 1911-1924.