No one ever suspected that sleep would have different stages, until researchers accidentally measured them. We usually pass through five stages of sleep: One, Two, Three, Four and Rem sleep. A complete sleep cycle takes around 90-110 minutes, with each stage lasting between 5 to 15 minutes.
Stages Of Sleep
Stages 1-4 are considered as NREM or Non-Rem sleep, followed by REM sleep (Rapid eye movement sleep).
Stage 1 is light sleep, where you can drift in and out of sleep and can be awakened easily. Eyes move slowly and muscle activity slows. People in this stage experience sudden muscle contractions, preceded by the sensation of falling.
- Although you are asleep, you wake up feeling like you haven’t slept at all.
- Blood pressure and heartbeat becomes regular.
- your eyes roll a little bit and you may slightly open your eyelids.
In stage 2 , eye movements stop and brain waves slow down. The body begins to prepare for deep sleep. We spend most of our nights in stage 2 sleep ( Around 45% of total sleep duration).
- Body temperature drops and heart rate slows down.
- Becomes hard to wake you up.
- Metabolic functions slow down.
- The first 2 stages of NREM sleep are known as light sleep.
When you enter Stage 3, you experience deep sleep. It is during this stage that a person may experience sleepwalking, night terrors, sleep talking and bed wetting. These behaviors are known as parasomnias and they occur during transitions from NREM to REM sleep.
In stage 4 , deep sleep continues and the brain produces more delta waves. People roused from this state feel perplexed for a few minutes.
- Stage 3 and 4 start 45 minutes after falling asleep.
- Our brain waves slow down and get amplified.
- At this point your noises and movements stop bothering you and you sleep through them.
The last stage is REM ( rapid eye movement) sleep. Throughout this stage, brain waves mimic activity during the waking state. The eyes remain closed however, they move rapidly from side-to-side. This rapid eye movements may be because of intense dreams and brain activity.
- Its the deepest stage of sleep and powerful dreams occur during this stage.
- Heart rate increases.
- REM stages get longer and longer as the night passes by.
- .REM and dreams overlap. However, they are not the same.
REM sleep is also known as paradoxical sleep because brain waves during this stage are very similar to those when you’re awake. Though most of your muscles are paralyzed, your brain shows heightened activity.
If you’re woken from REM sleep, you will end up right back in REM sleep in a later nap. REM sleep Deprivation impairs our ability to learn complex tasks and form long term memories.
edited by: Keerthana Suresh