Awakening during sleep

Waking phases are an intermediate state between wakefulness and sleep, and contribute to sleep-wake regulation. While clinically described as a single entity, they cover a wide range of EEG situations. Stereoscopic EEG has the potential to record intracranial activity in both superficial and deep structures. By combining this approach with polysomnography, researchers have defined two categories of awakening phases in sleep. They then studied local brain activity in 26 brain regions of 12 women. In both types of waking phase, intracranial theta, alpha, sigma and beta activities increased in 25 regions, while gamma and high-frequency activities decreased in 18 regions.