Association of Sleep Disruption With Daytime Sleepiness in Patients With Restless Legs Syndrome.

Objective: Patients with restless legs syndrome (RLS) often complain of nighttime hyperarousal which can be severe. Whether nocturnal hyperarousal is associated with excessive daytime sleepiness (EDS) remains understudied. This study aimed to compare the frequencies of self-reported and objective EDS between patients with RLS and controls, and to identify factors associated with EDS.

Methods: In this case-control study, consecutive untreated adult patients with moderate-to-severe RLS, and controls from the general population completed the Epworth Sleepiness Scale (ESS), Insomnia Severity Index, and Beck Depression Inventory II (BDI-II), at the Sleep Unit in Montpellier, France. International RLS study group severity scale (IRLSSQ) and RLS characteristics were recorded for patients. All patients and a subgroup of controls underwent a polysomnography (PSG) followed by multiple sleep latency test ([MSLT], abnormal latency <8 minutes). Logistic regression models were used to analyze the associations between clinical factors and (1) patients vs controls, and (2) self-reported EDS (ESS >10 vs ≤ 10), (3) objective EDS (MSLT <8 minutes vs ≥ 8).

Results: We recruited 162 patients with RLS (mean age 55.9 ± 12.5 y.o., 55.6% female) and 321 controls (mean age 56.1 ± 15.0, 55.1% female, 59 with MSLT). Patients with RLS had more insomnia and depressive symptoms than controls. Self-reported EDS (odds ratios [OR] = 13.7, 95% CI = [8.5-22.1], p < 0.0001) and objective EDS (OR = 7.0, 95% CI = [1.6-30.3], p = 0.009) were more frequent in patients than controls, in crude and adjusted models. Among patients, self-reported EDS was associated with increased IRLSSQ and BDI-II scores, and objective EDS. Objective EDS was associated with older age, male, withdrawal drug status before PSG, higher ESS score, shorter and fragmented sleep, periodic legs movements during sleep (PLMS), PLMS associated with arousals (PLMAs), and arousal indexes in patients with RLS. Associations between objective EDS, PLMS, PLMA, and arousal indexes remained significant after multiple adjustments. Multivariable analysis found that PLMA and ESS score were independently associated with objective EDS in RLS.

Conclusions: Self-reported EDS is a very frequent complaint in patients with RLS. Objective EDS is also frequent, especially in patients with severe PLMS, PLMA, and arousal indexes. Thus, EDS must be assessed and managed in current practice.