Sleep cycles consist of four stages: three non-rapid eye movement (non-REM) stages and one rapid eye movement (REM) stage. For optimal sleeping health and well-being, each healthy sleeping pattern should cycle through all four of these stages 4-6 times each night.
Consistency is key when it comes to getting a good night’s rest; creating and sticking to a bedtime routine will train your brain that it’s time for restful slumber.
Stages of Sleep
A healthy sleep cycle includes multiple stages that are depicted on what’s known as a hypnogram. This document displays each phase of sleep you go through each night; and can help identify issues in your architecture due to health problems like obesity or depression, sleeping disorders like restless leg syndrome or apnea or medications that might interfere.
Non-REM (NREM) sleep is light sleep that lasts one to five minutes and accounts for five percent of total sleep cycles.
At this stage, your breathing and heart rate begin to slow. Additionally, your eyes begin moving slowly back and forth as well. On electroencephalograms, brain activity in this stage looks similar to when awake; electroencephalograms show small bursts of activity called sleep spindles appear during this stage.
Grandner emphasizes the significance of light sleep for helping the body to maintain equilibrium, including managing appetite, metabolism, processing emotions and storing memories. Furthermore, light sleep may reduce inflammation, strengthen your immune system and assist with concentration during the day.
As soon as you enter the next phase of sleep, both heart rate and breathing begin to gradually slow. Your brain waves also start to slow down more gradually until they eventually resemble those seen during a deep slumber. It becomes hard for anyone to wake you up at this point in NREM sleep; your closest connection with reality may have vanished entirely!
Light Sleep
Your sleep cycle may appear passive, but there’s a lot happening inside of your body when sleeping. Each night your body cycles through four stages: light, deep, REM and awake; with light and deep sleep being predominant but REM sleep also an integral component. A healthy cycle should involve some amount of REM rest each night for optimal restful REM cycles.
Light sleep (also referred to as non-REM (NREM) stage 1) occurs as soon as you close your eyes and start sleeping. At this stage, your brain waves start slowing down from their regular rhythm and showing short bursts of activity known as sleep spindles; also during this phase your breathing, eye movement, and heart rate all decrease significantly.
Light sleep helps your brain process memories and emotions while your body regulates itself, as well as prepare you for deeper NREM phases by clearing away waste products and repairing muscle tissue. Light sleep may also bring dreams, although they are likely less vivid than during REM sleep.
This phase may vary in duration depending on who is sleeping, but generally takes several minutes. Your muscles become relaxed during this stage, leading to feelings of drowsiness when napping or awakening during the night. Achieve sufficient quality light sleep can improve mood, memory and daytime concentration levels.
Deep Sleep
Stage 2 sees your heartbeat and breathing slowing as you settle into non-rapid eye movement (NREM) sleep, although slight twitches may occur at first before relaxation sets in and it becomes harder for anyone to disturb you. Light brain activity continues, yet large delta waves start dominating EEG to signal your entry into deep sleep; during this restorative stage your immune system strengthens while your muscles grow and repair themselves; hormones released boost tissue growth while memory consolidation occurs during this stage – studies estimate we spend 20-25% of total sleep time here! Studies suggest we spend 20-25% of our total sleep time here!
After this stage, delta waves evolve into long and regular rhythms known as K-complexes that further reduce brain activity to levels below those seen during wakefulness. Your muscles relax as you enter an intensely restful state known as NREM sleep – only being awakened from deep periods during the final 90 minutes of any cycle and often without remembering any dreams that took place at that time.
After just a short period of REM sleep, brain activity returns to levels similar to what can be found during awakeness. You begin darting your eyes back and forth behind closed eyelids while dreaming occurs.
REM Sleep
Stage 1 non-REM sleep is an initial stage that occurs shortly after you fall asleep, easily disrupted, and lasts less than 10 minutes on average. Your heartbeat and breathing begin to slow while occasional bursts of rapid, rhythmic brain wave activity known as sleep spindles occur. Stage 2 non-REM sleep follows shortly afterwards for 20 minutes more and includes continued slowing of heart rate and breathing rate as you enter deeper sleep stages.
Stage 3 of non-REM sleep, also known as deep or slow-wave sleep, can be identified by measurements of brain waves. At this point, heart rate, breathing rate, body temperature and heartbeat all reduce significantly; also difficult to wake from this phase if disturbed; when done so however you are likely to feel disoriented for several minutes afterwards.
REM (rapid eye movement) sleep is the final stage of sleep wherein eyes move rapidly behind closed lids while brain activity quickly increases to mimic that seen during waking states. Your body experience paralysis except those necessary for breathing and eye movements; dreaming often takes place during this stage and scientists believe this process helps rejuvenate both mind and body during restful REM sleep.
