A human should sleep at least six hours a day. Sleeping is the most important thing to stay healthy. Sleep helps humans to wake up with a fresh mind without any muscle pain. In this fast-paced world, the sleep cycle differs often. Some people work rotational shifts and so they have to sleep as and when they have time. Every sleep cycle will have various stages which will work differently for every person. Are you wondering how many stages of sleep are there?  Here’s everything you need to know about the four stages of sleep psychology and its functions.

Four stages of the sleep cycle

One must have their sleep in any of the four different stages. One is REM (Rapid Eye Movement), and the other three comes under NREM (Non-Rapid Eye Movement). Most people’s sleep starts from NREM and ends in REM. However, there are some exceptions. Some people with insomnia and sleeping disorders won’t sleep for more hours. This would indicate that they are in REM more time than NREM.

What are the stages of sleep?

NREM sleep

NREM is the deep sleep stage compared to REM. The NREM stage consists of three phases such as N1, N2, and N3. Let us explore more about the different stages of sleep in the NREM.

  • NREM (N1)

N1 is the first stage of sleep. It would last one to five minutes. This phase is the falling asleep stage. One can easily wake up a person from N1. Yet if the person is undisturbed, he/she will enter into N2 in a few minutes as the night unfolds. At this stage, the human brain slows down its function, and your entire body will start relaxing.  

  • NREM (N2)

N2 is obviously the second phase of sleep. However, N2 indicates a deeper sleep than N1. During this stage, your body temperature drops, and your eye movement stops. You might be less aware of your circumstances as you start sleeping deep. Your muscles will be in a relaxed state and your breathing and heart rate will slow down. Gradually, your entire brain activity will reduce. N2 sleep would last for 10 to 25 minutes. However, you can experience the N2 throughout the sleep cycle often. On average, one would spend half of the sleep in the N2 stage.

  • NREM (N3) 

One would experience the deepest sleep in this stage. N3 would help your body to relax and repair. This way you can increase your insightful thoughts, creativity, and good memory skills. N3 will not only relax your muscles but also reduce your blood pressure. To set aside the past, and to start your fresh morning with good vibes, N3 is very much necessary for at least a few minutes. This deep sleep helps in strengthening your immune system and allows your body to work actively.

During this sleep, your brain will recollect certain facts and events which you have experienced or learned in life. N3 would last for 20 to 40 minutes and occurs mostly in the first half of your sleep cycle. As the sleep proceeds further, N3 would reduce and REM sleep will get more time.

REM sleep

As the name suggests, Rapid Eye Movement sleep is something that makes your eyes move quickly. At this phase, your body sleeps, and the brain arouses. Feeling weird? Yes, during REM, the organs of your body would be in an immobilized state, except the eyes and the muscles that allow you to breathe. That’s why you can’t respond to your dreams. Amazing! Right?

REM sleep begins approximately 90 minutes after you start sleeping and would last for 10 to 60 minutes. REM sleep is essential for cognitive development, memory, and learning. REM sleep will be longer in the second half of the sleep cycle. Typically, in the stages of sleep psychology in adults, REM sleep would occupy 25%.