Efficacy of modafinil on excessive daytime sleepiness in Prader–Willi syndrome

Excessive daytime sleepiness is a frequent and a highly disruptive symptom to the daily routine of children with Prader-Willi Syndrome (PWS) and their families. The objective of the study was to evaluate the efficacy of modafinil, a central stimulant, on excessive daytime sleepiness in children and adolescents with PWS. The efficacy of modafinil was evaluated in this open label pilot study comparing the Epworth sleepiness scale before and after treatment. Ten patients with molecularly confirmed PWS and a complaint of excessive daytime sleepiness underwent a night-time sleep recording and multiple sleep latency tests. One patient was excluded because of severe obstructive sleep apnea syndrome. Nine patients (4 males) with median age of 16 years (8-21) received modafinil at a starting dose of 100 mg/day. We found that all patients had excessive daytime sleepiness with an Epworth sleepiness scale at 14 (11-20) and mean sleep latency on multiple sleep latency tests at 5 (3-6) minutes. Moreover, six patients had at least two sleep-onset rapid eye movement periods showing a narcolepsy-like phenotype. Modafinil significantly improved sleepiness in all patients on the Epworth sleepiness scale from 14 (11-20) to 4 (3-12), (P = 0.007). Body mass index of the patients did not change significantly under treatment. No side effects were reported, and the drug was well-tolerated. We posit that this open label case series shows good efficacy of modafinil in nine children and adolescents with PWS.