In the context of physical and mental health, sleep plays a vital role in different aspects.
You have 4 distinct sleep phases that make up a cycle: Light sleep, deep sleep (SWS), rapid eye movement (REM), and wake.
A sleep cycle is comprised of 4 cycles and can be concluded in 90-120 minutes depending on the individual.
Each individual should be aiming to achieve 3-5 sleep cycles per night.
Even though each cycle is important, Deep sleep and REM are the most adaptive.
Deep sleep is the “physically restorative” phase, your muscles repair and grow, this is when 95% of your growth hormones are released, the biggest physical adaptions take place in this phase.
REM is the “mentally restorative” phase when ideas and skills acquired during the day are cemented as memories.
As it relates to an athlete, any time you are practicing a technical skill, the actual consolidation and retention of that learning happens during REM sleep.