Sudden onset of sleep and dopaminergic therapy in patients with restless legs syndrome

BACKGROUND AND PURPOSE: Sudden onset of sleep (SOS) was recently reported in patients with Parkinson's disease (PD) under dopaminergic treatment. Here, we investigated as to what extent SOS is found in patients with restless legs syndrome (RLS), who are frequently treated with dopaminergic drugs, and controls. PATIENTS AND METHODS: A questionnaire survey on SOS was administered to 156 RLS patients and 126 controls. RESULTS: While no significant difference between RLS patients and controls was detected in Epworth sleepiness scale (ESS) scores (P=0.76), the prevalence of SOS was higher in RLS patients (32.7%) than in controls (19.8%) (P=0.02). Significant predictors of SOS in RLS were ESS score (odds ratio (OR) 16.4), male sex (OR 4.6), duration of night-time sleep (OR 3.0), and age (OR 2.9), while no association was observed for duration or severity of the disease. Patients on dopaminergic therapy usually featured a lower risk of SOS than untreated patients. Falling asleep while driving was reported by 14.6% of all RLS patients with a driver's license and associated with increased risk of accident (OR 7.1). CONCLUSIONS: RLS patients who are untreated, male, and elderly should be assessed for the presence of SOS. In contrast to PD, dopaminergic drugs may reduce the risk of SOS in RLS. The possible benefit of the drugs should be investigated particularly in male patients.