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,
Sleep and memory eye movement" (NREM) sleep whereas the last cycle is a rapid eye movement period. A cycle takes approximately 90–110 minutes to complete. Wakefulness is found through EEG measures to be characterized by "beta waves" which are the highest in frequency and lowest in amplitude and tend to move inconsistently due to the vast amount of stimuli a person encounters while awake. During the first half of the night, the largest portion of sleep is spent as SWS, but as the night progresses SWS stages decrease in length while REM stages increase. Stabilization of a memory is the anchoring of a