Restless legs syndrome (RLS) and periodic limb movement disorder (PLMD) - Acute placebo-controlled sleep laboratory studies with clonazepam

Restless legs syndrome (RLS) - a common sensorimotor disorder - and periodi c limb movement disorder (PLMD) are currently treated with substances of fo ur classes: dopaminergic agents, which are considered the drugs of choice, benzodiazepines, opioids and anticonvulsants. As their effects on sleep var iables differ considerably, the aim of the present placebo-controlled sleep laboratory study was to measure the acute effects of 1 mg clonazepam on ob jective and subjective sleep and awakening quality in ten RLS and 16 PLMD p atients, utilizing polysomnography (PSC) and psychometry. Descriptive data analysis demonstrated at the confirmatory level concerning three target var iables that - as compared with placebo - clonazepam significantly improved objective sleep efficiency and subjective sleep quality in both patient gro ups, but failed to reduce the index PLM/h of sleep. At the descriptive leve l, in PLMD clonazepam improved PLM during rime in bed, REM and wakefulness and showed more significant changes in various sleep and awakening measures than in RLS patients, though there were no significant inter-group differe nces. In conclusion, in both PLMD and RLS clonazepam exhibited acute therap eutic efficacy regarding insomnia, which is quite different from the mode o f action of dopamine agonists. (C) 2001 Elsevier Science B.V. All rights re served.