The Depths of Sleep
As one transitions into deeper stages of non-REM sleep, remarkable physiological changes occur, including a significant drop in heart rate and a unique synchronization of brain activity. This phenomenon resembles a meditative rhythm, characterized by large brainwave patterns that are unlike any other state of consciousness. The coordination of brain cells during this phase highlights the intricate processes involved in restorative sleep.In this clip
From this podcast

Huberman Lab
Dr. Matthew Walker: The Science & Practice of Perfecting Your Sleep | Huberman Lab Podcast #31
Related Questions
Tell me about Stage 1 (NREM 1) sleep:
Does sleep normally go from non-REM stages 1-3, then REM, complete one cycle, and then start with non-REM stage 1 again?
Is it correct that sleep is divided into two main stages, Non-Rapid Eye Movement (NREM, deep sleep, non-dreaming) and Rapid Eye Movement (REM, dreaming), and that NREM sleep is further divided into alpha, theta, and delta stages, as discussed in the episode Dr. Matthew Walker: The Biology of Sleep & Your Unique Sleep Needs | Huberman Lab Guest Series? Additionally, is it true that the NREM and REM stages alternate within each 90-minute cycle, with more time spent in NREM during the first half of the night and more time in REM during the second half, as discussed in the clip Sleep Architecture Insights?