**1. Introduction**

For centuries, the intimate and reciprocal interaction between epilepsy and sleep was well recognized. In the late 1800s, Gowers investigated the relationship between grand mal epilepsy and the sleep-awake cycle [1]. In 1929, Langdon-Down and Brain found that nocturnal seizure occurrence had two peaks, approximately 2 h after bedtime and between 4 and 5 am, and daytime seizures occurred predominantly in the first 2 hours of awakening [2]. These conclusions were at first based solely on clinical observations. However, the advent of the electroencephalogram (EEG) revealed that sleep not only activated clinical seizures, but also interictal epileptiform discharges (IEDs), thus sleep and sleep deprivation becoming the standard laboratory activating techniques during the EEG recording. Epilepsy may also affect sleep architecture.

This chapter is an overview of the relationship between sleep and epilepsy.
