The role of large muscle movements on excessive daytime sleepiness in patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is a heterogeneous disorder requiring personalized diagnostic approaches. Restless sleep and excessive daytime sleepiness (EDS) frequently accompany OSA, and are mainly linked to sleep fragmentation secondary to apneas and/or hypopneas. In this study, we aimed to analyze the characteristics of LMMs in OSA and to evaluate interrelationship between LMMs and EDS.

Untreated-naïve adult OSA patients, with vs. without EDS were prospectively enrolled. Patients with comorbid neurological/psychiatric diagnosis, usage of drugs/substances known to affect sleep and positive airway pressure therapy were excluded. Routine evaluation of video-polysomnography was followed by LMM scoring. LMMs were compared between OSA with vs. without EDS, and correlations of LMMs with ESS scores and macrostructural sleep parameters were analyzed.

Sixty patients were included (median age 43.5 [37.0] years, %78.3 men); 17 had EDS with Epworth Sleepiness Scale (ESS) ≥ 10 (28.3%). Total LMM index in total sleep time (TST) was 7.9 [20.6]. Total LMM index in TST (p = 0.048) and N1 (p = 0.020), and arousal-related LMM index in TST (p = 0.050) and N1 (p = 0.026) were higher in OSA with EDS than those without EDS. ESS scores were positively correlated with total (r = 0.332,p = 0.028) and arousal-related (r = 0.338,p = 0.025) LMM indexes in N1, and abnormal respiratory event-related LMM indexes in N1 (r = 0.440,p = 0.003) and N3 (r = 0.293,p = 0.050) after correction for age, sex, body-mass-index and apnea-hypopnea index.

Our study demonstrated that LMMs were more frequent in OSA with EDS than those without EDS. This may have broad implications for the mechanisms of motor restlessness and residual sleepiness in OSA and warrants larger-scale, long-term follow-up studies.

No clinical trial registration due to the observational design of the study.