Sleep is an essential part of the everyday life. Epilepsy and sleep disorders are considered by many to be common bedfellows. Sleep can affect seizure occurrence, threshold, and spread, while epilepsy can have a profound effect on the sleep/wake cycle and sleep architecture. The etiology of sleep disruption in patients with epilepsy is multifactorial and includes factors such as inadequate sleep hygiene, coexisting sleep disorders, circadian rhythm disturbances, epilepsy per se, seizure frequency, and the effect of antiepileptic medications. A series of manuscripts in this issue further attempt to define the complex relationship between epilepsy and sleep.