This research study is designed to understand the relationship between sleeping patterns and epilepsy. In many epilepsy patients, abnormal brain activity (interictal spikes) and sometimes seizures are more common during sleep. By finding out which part of sleep shows the most abnormal brain activity, we hope to understand better how seizures start and how they can be prevented. We are recruiting adult and pediatric subjects with epilepsy from the University of Michigan Clinics and Epilepsy Laboratory for participation in this study. Subjects, ages 5-65, have a history of epileptic seizures within the last three months and are able to cooperate with an overnight sleep-EEG study. They do not have nonepileptic spells, seizures provoked by medical causes alone, or concurrent major medical or psychiatric disorders. All subjects undergo two consecutive nights of testing in the General Clinical Research Center. To study sleeping patterns, a variety of electrodes and sensors are temporarily glued to the scalp, around the eyes and lips, on the chin, ear lobe, finger, chest, and abdomen while the subject sleeps. The sleep tests are standard tests that have been used throughout the USA. During the day after the first night of testing, subjects participate in a series of naps called the Multiple Sleep Latency Test. This test allows us to record EEG activity at the onset of sleep and allows us to measure how sleepy a subject is compared to other subjects. Our measurement outcomes are interictal spikes (abnormal brain activity during sleep) and the degree of sleepiness. We perform visual and computer analysis of the relationship of interictal spikes to sleep and to sleepiness to determine the times of the sleep cycle where abnormal brain activity is most prominent. Our long term goal is to predict and prevent seizures in patients with epilepsy.