The relationship of sleep and epilepsy demonstrates the delicate association of brain physiology and dysfunction. Sleep affects the distribution and frequency of epileptiform discharges in humans and influences the rate of kindling in animals. Epileptic discharges, on the other hand, alter sleep regulation and provoke sleep disruption. This effect on sleep appears to carry over to sleep complaints in patients with epilepsy. Individuals with epilepsy frequently complain of symptoms suggestive of disturbed sleep, such as excessive daytime sleepiness, insomnia, or with more subtle complaints such as an increase in seizure frequency. More commonly, these symptoms indicate an underlying sleep disorder rather than the effect of epilepsy or medication on sleep. Clinicians must be able to identify and differentiate between potential sleep disorders and sleep dysfunction related to epilepsy and direct therapy to improve the patient's symptoms. The reciprocal relationship of sleep and epilepsy and the management of sleep complaints in the patient with epilepsy will be reviewed.