Memantine-induced delayed sleep phase in Huntington's disease: A case report.

Circadian rhythm sleep disorders may occur after memantine administration. We describe a 49-year-old woman with Huntington's disease, who complained of sleep onset insomnia following the administration of memantine. Memantine reduced hyperkinetic movements but led to delayed sleep phases, that were dose-dependent and reversible, confirmed by sleep logs and actigraphy.