To know more about stages of non-REM sleep, you must have a fair and comprehensive understanding of how your body works while you sleep. Once you sleep, your body still remains awake during the early phases. During this time, your brain produces delta waves that are known for being small and fast. Once the brain starts slowing down, your brain starts producing alpha waves which are relatively slower in nature.
What Are The 4 Stages Of Non-REM Sleep?
Your body might experience strange sensations during this time. These sensations are medically known as hypnagogic hallucinations. If you have experienced falling just after sleeping, that was this kind of hallucination. Many people also go through myoclonic jerk which is quite common.
What is Non-REM Sleep?
Non-Rem sleep can be defined as dreamless sleep. If you are sleeping for 7-8 hours a night, it is highly likely that you are spending one and a half hours sleeping dreamless NREM sleep. Your brain starts releasing slow waves during non-REM sleep. Besides having a high voltage, these waves cause the breathing and heart rate to slow down.
Four Stages of Non-REM Sleep
Non-REM sleep can be divided into four stages i.e. stage 1, stage 2, stage 3, and stage 4. Stage 1 happens during the beginning of the sleep cycle. As you continue sleeping, your body experiences all these stages one by one. Here are four stages:
- N-REM Stage 1: Stage 1 takes place during the initial phase of the sleep cycle. This is actually the transition period between wakefulness and sleep. As your body goes into this light stage of sleep, your brain starts producing high amplitude theta waves. These brain waves are slower in nature. Lasting for around 10 minutes, this stage makes you feel that you were not really sleeping.
- N-REM Stage 2: During stage 2, people start being less aware of their surroundings. It is during this phase when your body temperature drops. Breathing along with heart rate starts becoming more regular. Lasting approximately for 20 minutes, this stage compels the brain to produce rhythmic brain waves which are also known as sleep spindles. You will be experiencing decreased body temperature and slower heart rate as the brain produces these rapid brain waves. According to a study conducted by the American Sleep Foundation, most people spend around 50% of the entire sleep in this stage.
- N-REM Stage 3: As your body enters the third stage, your muscles start relaxing and you experience the deepest sleep. It is during this phase when both your blood pressure and breathing rate start dropping. Your brain starts producing slow brain waves i.e delta waves during this time. That’s why many refer to this sleep as delta sleep. Since your body becomes less responsive to any noise in the surrounding area, even a chaotic environment may fail to generate a response in your body. Acting as a transition period between light sleep and deep sleep, this stage helps your body to heal. According to a study, bed-wetting often happens at this stage. And, even people are more prone to engage in sleepwalking during this stage.
- N-REM Stage 4: There isn’t much difference between stage 3 and stage 4. The only difference is that stage 4 is more intense than stage 3. During this stage, your body starts repairing and regenerating tissues. Not only this stage helps you to strengthen your immune system but also paves the path for you to build bone and muscle. As you start getting older, you start experiencing less amount of NREM sleep. While people under 30 might be experiencing up to two hours of restorative sleep, people above 60 might get only 30 minutes of non-rem sleep.
What Happens During REM Sleep?
During REM sleep, your brain becomes more active while your body starts relaxing more. Dreams occur during this period of time and rapid eye movement happens as well. Most of the people spend 20% of the total sleep in this stage. During REM sleep, you will be experiencing increased brain activity and elevated respiration rate as well. REM sleep is also known as paradoxical sleep since your muscles become relaxed despite the brain along with other body parts being active. As you dream at night, your brain activity increases whereas voluntary muscles remain immobilized most of the time.
You start experiencing REM sleep after 100 minutes of sleep. Every cycle of REM sleep takes place at an interval of 90 minutes. Being longer than non-REM sleep in terms of duration, REM sleep causes the breathing rate to increase and eventually become irregular. During this phase, your body starts producing chemicals that temporarily paralyze your muscles and therefore prevent you from acting out dreams. Despite the brain being active, muscles tend to rest during this time.