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 sleepers during a REM phase is a common experimental method for obtaining dream reports; 80% of neurotypical people can give some kind of dream report under these circumstances. Sleepers awakened from REM tend to give longer more narrative descriptions of the dreams they were experiencing, and to estimate the duration of their dreams as longer. Lucid dreams are reported far more often in REM sleep. (In fact these could be considered a hybrid state combining essential elements of REM sleep and waking consciousness.) The mental events which occur during REM most commonly have dream hallmarks including narrative structure, convincingness (experiential