How Do Restless Legs Syndrome Patients Recognize Daytime Sleepiness? - The Multiple Sleep Latency Test -

Abstract

Background and Objective Restless legs syndrome induces sleep fragmentation and impairs sleep quality. Although insomnia is the most frequently reported symptom, a substantial proportion of patients report excessive daytime sleepiness (EDS), and the factors that contribute to EDS need to be assessed for optimal treatment. Methods Sixty-five untreated idiopathic restless legs syndrome (RLS) patients underwent polysomnography (PSG), multiple sleep latency test (MSLT) and the suggested immobilization test (SIT). After excluding nine patients with more than two sleep onset REM (SOREM) in the MSLT, and 15 patients with an apnea-hypopnea index of ≥ 10/hr, 41 patients were finally included. The severity of EDS was evaluated using the Epworth sleepiness scale (ESS), and the severity of RLS by International RLS Study Group Rating Scale (IRLS), and SIT. RLS patients were sub-grouped into sleepy RLS (S-RLS) (ESS > 10), and non-sleepy RLS (NS-RLS) (ESS ≤ 10). Results The mean age upon evaluation was 54.56 ± 11.91 years of age (female: 70.7%), and the duration of RLS before diagnosis was 11.87 ± 10.65 years. RLS patients had decreased sleep efficiency, increased arousal indexs, increased periodic limb movements during sleep (PLMS) index, and movement arousal index (MAI) by PSG. There were nine patients (22%) in the S-RLS group, and 32 patients (78%) in the NS-RLS group. IRLS severity was significantly higher in the S-RLS than in the NS-RLS group (p = 0.023). The seven patients with SOREM had a mean REM latency of 2.81 ± 5.4. Correlation analysis revealed a negative correlation between the MSLT mean sleep latency and the PLMS index (p = 0.003, ρ = 0.463) and MAI (p = 0.040, ρ = 0.334). Conclusions EDS is frequent in RLS-PLMS patients and subjective sleepiness was found to be higher in patients that reported severe RLS symptoms.

Keywords

• Restless legs syndrome
• Daytime sleepiness
• Multiple sleep latency test