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,
PGO waves and subthalamic nucleus (or subthalamus). This latter, glutamatergic nucleus is reciprocally connected with the PGO-transferring nuclei of the pons. In humans, subthalamic PGO-like waves, that resemble the PGO waves typically recorded in cats, can be recorded during pre-REM and REM sleep. This suggests that the subthalamus may play an active role in an ascending activating network implicated in the rostral transmission of PGO waves during REM sleep in humans. PGO waves are an integral part of rapid eye movement (REM) sleep. As stated earlier, the density of the PGO waves coincides with the amount of eye movement measured in REM