This issue on Sleep Electroencephalography (EEG) gives an overview of Electrophysiological readings in sleep with such articles as “The Nuts and Bolts of EEG” and “How the Sleep/Wake EEG Changes Across the Lifespan.” Identifying abnormal EEG activity and patterns in the Electroencephalographic readings is also discussed. The issue then further focuses in on Seizures and the EEG; specifically, how EEG can be used to diagnosis and identify seizure disorders and differentiate seizures from other paroxysmal nocturnal events, and to diagnose other primary sleep disorders in people with epilepsy.