Arousals

Arousal from sleep is a natural phenomenon and evolutionarily protective but may contribute to sleep disruption and daytime dysfunction. Arousals are classically defined as an abrupt change in EEG frequency but may occur in the absence of discernible EEG change. Arousals play an important role in the scoring of respiratory events and are typically identified visually although advances in automated arousal detection and surrogate markers of arousal are being developed. Mechanisms underlying arousals and the role of arousal threshold in sleep disordered breathing and other disorders are reviewed.