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Over the last few years, more and more people have become aware of the benefits of good sleep. There has been a steady rise in the number of sleep accessories being bought.
Thanks to sleep trackers, people are aware of the importance of sleep cycle stages or 5 stages of sleep. It has a significant role in better sleep and waking up fresh.
Most people tend to categorize the sleep cycle into the REM (rapid eye movement) cycle and the non-REM (NREM) cycle. But the NREM cycle itself has 4 phases of sleep. The quality of sleep has a direct correlation with the amount of sleep you get in each sleep cycle.
REM and NREM sleep occurs alternatively. Normal sleep on a given night usually contains 4-6 sleep cycles. Each cycle typically lasts around 90-100 minutes. The later sleep cycles have longer REM sleep time with non-REM sleep time gradually decreasing.
Let us understand the 5 different stages of sleep in a more lucid way.
What are the 5 Stages of Sleep?
Stage 1: Non-REM – Falling Asleep
This is the first stage of sleep that begins when you start falling asleep. It is a period of light sleep and you may get awake easily even with the slightest disturbance. The stage is a really short duration.
In stage 1
- Heart rate slows down.
- Body temperature drops.
- Breathing is slow and muscles tend to relax.
Stage 2: Non-REM – Light Sleep
This stage lasts around 25 mins with light sleep. It sets the stage for deep sleep.
In stage 2
- Breathing further slows down and the heart rate remains lower.
- Negligible to no eye movement.
- Body temperature is low.
- There is a burst of neural activity called sleep spindles.
Stage 3: Non-REM – Deep Sleep Phase 1
This is the stage when you go into a deep sleep. Stages 3 and 4 are crucial for the brain to relax and recover. There are multiple health-related activities that happen during deep sleep.
In stage 3
- Body repairs and promote muscle growth in the body.
- Blood pressure goes down.
- It is very difficult to wake up from deep sleep. If you get woken up, you will feel disoriented and may find it difficult to go back to sleep.
- Brain wave slows down.
Stage 4: Non-REM – Deep Sleep Phase 2
In this stage, the body further goes deeper into sleep.
During stage 4
- Growth hormones are released.
- Tissue repair happens during this stage.
- It is also responsible for strengthening the immune system.
- Delta waves are produced in the brain.
- There is no eye movement in deep sleep.
Stage 5: REM Sleep
Roughly after 90 minutes, the body enters into the rapid eye movement phase or REM sleep cycle. This is the stage where a human starts dreaming leading to eye movement. The first REM sleep cycle is the shortest and it increases in every cycle.
It is again the shortest at the end of your sleep cycle.
During stage 5 of the REM cycle
- The breathing rate is high and shallow.
- There is rapid eye movement.
- Blood pressure and heart rate are high.
- Limbs are almost paralyzed to avoid any body activity during the dreams but there may be slight twitching.
- Brain wave activity is high. There is information sorting that results in learning and increased memory.
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