The purpose of this study is to collect continuous observational data during a clinical Epilepsy Monitoring Unit evaluation.

Observational, unblinded, non-randomized, multisite study designed to collect data on up to 500 subjects undergoing evaluation for epilepsy in EMUs. Subjects currently enrolled or that previously participated in this study may be eligible for the E-30-S sub-study.

Inclusion Criteria:

Patients enrolled in the study must meet all of the following criteria:

1. Patient has a clinical diagnosis of epilepsy requiring evaluation in an epilepsy monitoring unit (EMU).
2. Patient likely requires an EMU evaluation for a period of at least 24 hours.
3. Patient is currently taking at least one antiepileptic medication.
4. Patient must be in good general health and fully ambulatory.
5. Patient or guardian must be willing and able to complete informed consent/assent and HIPAA authorization.

Exclusion Criteria:

Patients who meet any of the following criteria are not eligible to be enrolled in the study:

1. Patients with severe psychiatric disease that in the investigator's judgment would prevent the patient's successful completion of the study.
2. Patients with a history of status epilepticus.
3. Patients prescribed drugs specifically for a cardiac or autonomic disorder that in the investigator's opinion would affect heart rate response. Drugs with secondary cardiac or autonomic actions are allowed.
4. Patients with cardiovascular arrhythmias or cardiac disease that would preclude the ability to detect intrinsic changes in heart rate due to exercise, stress, or seizure. This would include but not be limited to chronic atrial fibrillation, chronotropic incompetence, and permanent cardiac pacemaker implantation.
5. Patients with a history of dependence on alcohol or narcotic drugs within the past 2 years as defined by DSM IV-R.

Epilepsy patients indicated for epilepsy monitoring unit stay.