Sleep and epilepsy: Strange bedfellows no more

Ancient philosophers and theologians believed that altered consciousness freed the mind to prophesy the future, equating sleep with seizures. Only recently have the bidirectional influences of epilepsy and sleep upon one another received more substantive analysis. This article reviews the complex and increasingly recognized interrelationships between sleep and epilepsy. Non-rapid eye movement (NREM) sleep differentially activates interictal epileptiform discharges during slow wave (N3) sleep, while ictal seizure events occur more frequently during light NREM stages N1 and N2. The most commonly encountered types of sleep-related epilepsies (those with preferential occurrence during sleep or following arousal) include frontal and temporal lobe partial epilepsies in adults, and benign epilepsy of childhood with centrotemporal spikes (benign rolandic epilepsy) and juvenile myoclonic epilepsy in children and adolescents. Co-morbid sleep disorders are frequent in patients with epilepsy, particularly obstructive sleep apnea in refractory epilepsy patients, which may aggravate seizure burden, while treatment with nasal continuous positive airway pressure often improves seizure frequency. Distinguishing nocturnal events such as NREM parasomnias (confusional arousals, sleep walking, and night terrors), (rapid eye movement, REM) parasomnias including REM sleep behavior disorder, and nocturnal seizures frequently difficult and benefits from careful history taking and video-EEG-polysomnography in selected cases. Differentiating nocturnal seizures from primary sleep disorders is essential for determining appropriate therapy, and recognizing co-existent sleep disorders in patients with epilepsy may improve their seizure burden and quality of life.