In some patients with Epilepsy, seizure activity is associated with specific phases of sleep/wake cycle, and sleep deprivation is known to precipitate seizure activity. Inadequate or disturbed sleep and excessive daytime drowsiness is often reported by patients with Epilepsy due to the effects of seizures as well as antiepileptic drugs. Thus, the use of healthy subjects improves the certainty that any changes in sleep are related to the study drug and not other factors.