All you need to know about Sleep Cycle and Stages

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Sleep is just as essential for us as eating healthy food and exercising and also for many other brain functions.
Including how nerve cells (mean neurons) communicate with each other.
During sleep, our body moves through five stages of REM and NREM.

  • REM stands for rapid eye movement.
  • NREM stands for Non-rapid eye movement.

Each step of sleep has a unique function including muscles recovery and memory consolidation.


"NREM 1" is the first stage of sleep when one finds themselves in consciousness during sleep.
Stage one is a period of drowsiness, and in this stage, it’s easy to wake up someone from sleep. Sometimes they can be awake by a loud noise or any loud movement. In NREM 1, the muscles of our body jerk.
Although you spend only 5-12 minutes in this stage but you may spend more time in this phase if you are suffering from insomnia or stress.


Stage two is also a non-REM (non-rapid eye movement) phase and is one of the lighter stages of sleep. In this non-REM, your breathing rate and heartbeat rate becomes slow, and the temperature of the body also decreases.
Movement of eye stops and brain waves slow which is known as sleep spindles. You can still wake someone up from sleep but can recognize that they were sleeping.
Research shows that 50% of the time we spent in this stage which is around about 10-25 minutes.

STAGE #3 & 4

In 2007, the American Academy of Sleep Medicine combined the third and fourth stages, these stages are known as the deep stages of sleep and are often the hardest to wake up from.
If you awake suddenly from stage 3 or 4, you will feel be groggy for minutes. The sleep of three or four stage is one of the deepest sleep stages in which your body enters during the sleep.
It is called slow wave sleep in which blood pressure will slowly drop.
Your body will repair by itself, and it can last for up to an hour or more, during this stage the blood supply to your muscles will increase gently.

old illustration of kid sleeping on a bed


Stage five is referred to as dream sleep and is the stage of rapid eye movement (REM). It is the stage where someone starts to dream.
It is an essential stage of sleep for your emotional health as brain activity increases and your heart beat rate also.
Research shows that most adults spend about 20% of sleep in REM, while on the other hand infants spend almost 50% of their sleep in this stage.
During non-REM sleep, our mind rests while the body heals, but in REM sleep the mind energizes itself. Individuals begin waking up at the end of stage 5.

Understanding that how these sleep cycles work is essential in order to maintain a healthy mind and body and it helps you get quality, uninterrupted sleep each night.