Dopaminergic treatment in idiopathic restless legs syndrome: effects on subjective sleepiness.

OBJECTIVES: To assess frequency and characteristics of excessive daytime sleepiness (EDS) in restless legs syndrome (RLS) and the evolution of EDS under different RLS therapies.

METHODS: We analyzed data from the "Swiss RLS" study, which was conducted to compare treatment efficacy and safety of the dopamine agonist pramipexole (PPX) versus L-dopa/benserazide (L/B) in de novo patients with idiopathic RLS and performed as a randomized, double-dummy, comparative crossover trial. Primary outcome measure of the present study was the change in subjective sleepiness (as measured by Epworth sleepiness scale [ESS] score). There were 37 patients (21 women) included. Mean age was 56.6 years (range, 25-85 years), and mean body mass index was 24.6 (SD, ±3.5).

RESULTS: At baseline, EDS (as determined by an ESS score of >10) was found in 32% of the patients. Sleepy RLS patients were younger (P < 0.001) than non-sleepy patients. Pramipexole and L/B both were effective in the treatment of RLS symptoms (IRLS score, P < 0.001 and P = 0.002). Overall, ESS was reduced (main effect for "time", P = 0.02) independent from the dopaminergic substance. In 5 of 37 patients, ESS score deteriorated to greater than 10 under treatment (PPX = 3 patients, L/B = 2 patients). No sleep attack occurred.

CONCLUSIONS: Excessive daytime sleepiness is frequent in RLS patients. Dopaminergic treatment usually promotes wakefulness, but infrequently leads to daytime sleepiness.