The brain has four stages within the NREM phase.
Each stage and phase of sleep plays an important role in our overall health.
This brief transition typically lasts only a few minutes.
Halfpoint Images / Getty Images
During this stage, yourheart rateand breathing slow down.
Some people may experiencemuscle twitchesas the muscles start to relax.
The brain waves during stage 1 NREM sleep transition from daytime patterns to nighttime patterns.
The heart rate and breathing continue to slow down, and the muscles continue to relax.
During stage 2 NREM, thebody temperaturedecreases, and the eyes stop moving.
The brain begins to have slow-wave activity.
This stage lasts between 30 and 60 minutes.
It is the part of the sleep cycle that allows us to feel refreshed in the morning.
It is also the stage of sleep during which the body repairs and regenerates tissues and releases certain hormones.
During this stage of sleep, breathing and heart rate have slowed down.
A person’sblood pressurehas decreased, and the muscles are relaxed.
This stage moves information from temporary to permanent memory.
This may be why some recommend that you “sleep on it” when making important decisions.
REM sleep starts about 90 minutes after someone has fallen asleep.
During this stage, the body activity changes dramatically from the other stages of sleep.
Deep sleep occurs during stage 3 of non-rapid eye movement (NREM) sleep.
REM sleep occurs after that.
During deep sleep, your body makes physical repairs to its tissues.
Deep sleep and REM are equally important.
However, frequent or long interruptions can affect a person’s health.
A 2017 review looked at the short- and long-term consequences of sleep disruption.
The NREM phase is broken down further into three stages.
Each phase and stage of sleep is restorative to the brain and body.
Contact a healthcare provider if you have concerns about your sleep.
National Institute of Neurological Disorders and Stroke.Brain basics: understanding sleep.
Kaiser Permanente.Stages of sleep.
Harvard Health Publishing.Sleep stages and memory.
Medic G, Wille M, Hemels ME.Short- and long-term health consequences of sleep disruption.Nat Sci Sleep.
2017 May 19;9:151-161. doi:10.2147/NSS.S134864
