Non-REM sleep, specifically slow wave sleep, is characterized by a pattern of brain activity involving slow, sweeping waves across large areas of the brain. During this stage, the brain remains metabolically active but biases certain circuits to be more or less active, influenced by neuromodulators such as acetylcholine, norepinephrine, and serotonin. These neuromodulators function similarly to music playlists, suggesting different genres of neural activity 1.

Non-REM sleep is divided into four stages, with stages three and four being deep sleep where significant physiological changes occur. In deep non-REM sleep, heart rate drops, and large groups of neurons in the cortex exhibit coordinated firing and silencing, a phenomenon not seen during other brain states 2 3. This deep sleep is crucial for various bodily functions, including cardiovascular health and immune system maintenance. It helps calm the nervous system and promote healing and recovery 4.

Slow Wave Sleep

Andrew explains the characteristics of slow wave sleep, including the sweeping waves of brain activity and the neuromodulators associated with it. He compares neuromodulators to music playlists, biasing particular brain circuits towards certain genres of neural activity.

Huberman Lab

Understanding and Using Dreams to Learn and to Forget | Huberman Lab Podcast #5

The architecture of sleep cycles predominantly features deep non-REM sleep in the earlier part of the night, shifting to more REM sleep in the latter part. This structure impacts how sleep deprivation affects different stages of sleep, with early sleep loss primarily affecting REM sleep 5.