Non-rapid eye movement sleep activation occurs during NREM that is comparable to the type that occurs during REM. It is this sub-cortical activation that results in dreaming during the NREM stage during the morning hours. During non-REM sleep, the tonic drive to most respiratory muscles of the upper airway is inhibited. This has two consequences: However, because the diaphragm is largely driven by the autonomous system, it is relatively spared of non-REM inhibition. As such, the suction pressures it generates stay the same. This narrows the upper airway during sleep, increasing resistance and making airflow through the upper airway turbulent and noisy. For example,
Rapid eye movement sleep This reflex, also known as animal hypnosis or death feigning, functions as the last line of defense against an attacking predator and consists of the total immobilization of the animal so that it appears dead. Tsoukalas argues that the neurophysiology and phenomenology of this reaction shows striking similarities to REM sleep; for example, both reactions exhibit brainstem control, paralysis, hypocampal theta rhythm, and thermoregulatory changes. According to "scanning hypothesis", the directional properties of REM sleep are related to a shift of gaze in dream imagery. Against this hypothesis is that such eye movements occur in those born blind and in