Cyclic Alternating Pattern (CAP) is a type of sleep disorder characterized by recurrent changes in sleep-wake states that occur in a cyclical fashion throughout the night. It is associated with other sleep disorders such as obstructive sleep apnea, insomnia, and restless leg syndrome. CAP is classified as a parasomnia, which is a type of sleep disorder that can occur during sleep or wakefulness. People with CAP often experience periods of deep sleep alternating with periods of shallow sleep, or brief awakenings during the night.