It is well known that clinical and EEG manifestations of many epilepsy syndromes are related to sleep-and-waking cycles. Epilepsies are thought as disorders reflecting abnormalities in neuronal networks underlying sleep process. Patients with epilepsy, on the other hand, are generally reported to have poor sleep quality when compared with healthy controls. Furthermore, poor sleep quality or sleep-deprivation may worsen seizure control and set a vicious cycle. Anti-epileptic drugs may also affect sleep architecture. Here, we aim to review the complex relationship of sleep and epilepsy in the light of relevant literature.