Sleep Cycle- What are the different stages of Sleep?

The sleeping process is not a simple one. Doctors and researchers of ancient times believe the fact our brain completely stops working while sleeping and reboot itself like a computer for the next day. Well, the modern sciences have proven it to be wrong. As scientists discovered the complexities and processes a human body goes through during a night’s sleep, they realized different stages of sleep that depict different states of the brain. In some sleeping stages, the brain can tend to be even more active compared to when it’s awake.

So, let’s discuss how a sleep cycle works and what are the different stages of sleep:

Our sleep is basically categorized into two major patterns: REM (Rapid Eye Movement) and NREM (Non-Rapid Eye Movement). REM sleep is usually lighter making it an active sleeping stage. This category of sleep is basically associated with dreaming. However, NREM on the other hand depicts the deeper sleep stages. In healthy sleep, a human goes through each of the following sleep stages, each having a cycle of about 90 minutes lasting up to 110 minutes.

1.     Stage 1: Transition

The first Non-rapid eye movement stage is a light one. It’s the drowsy sleep we encounter not so long after hitting the bed. During this stage our muscle relaxes, our brain’s activity slows down and a light wave of drowsiness takes over us. This stage of sleep can easily be disrupted by noise, some recurring movement, etc. If you have ever experienced that sudden falling sensation within the sleep, it’s likely to happen in NREM’s early stages when sleepers can experience muscle spasms and hypnic jerks. We usually stay in the transition state during our cat naps.

2.     Stage 2: Light Sleep

This specific stage makes about 40-60% of our night’s sleep. During this stage, our brain produces waves of certain frequency generally known as sleep spindles that refresh our brain, relax it, and make it prepared for learning and absorbing more information. In the light sleep stage, our brain starts showing the slow-wave activity patterns that mark the starting of the third stage. When people categorize their sleep to power naps, they usually wake up right after the second sleeping stage. To enter into the third stage called deep stage our body’s temperature begins to drop and heart rate slows down.

3.     Stage 3: Deep Sleep

Deep Sleep is usually shorter compared to the previous stages making a total of 5-15% of your sleep cycle. This is the most restorative sleep we get during the night when there’s practically no eye movement and a human body encounters the lowest muscle movement. A human body is least likely to get affected by the external stimuli during deep sleep, as the delta waves produced by the brain are extremely slow. If one manages to wake up from deep sleep he/she might feel disoriented for good 5-10 minutes.

4.     Stage4: REM Sleep

Rapid Eye Movement (REM) stage can occur anytime during our sleep cycle but usually happen after 90 minutes of sleep. Research shows that most of the adult’s experience about 4-5 REM throughout their night’s sleep. REM period of the night is fairly short during the start of the sleep cycle. The first period of REM lasts for about 10 minutes and each session becomes lasting after the first. During the REM sleeping stage, both our heart and brain start picking up pace. This particular sleeping stage is considered the most active of all the sleeping stages.

We hope the article must have been of help in understanding different stages of sleep. Leave your feedback in the comment section below.