Different Phases Of Sleep

The most crucial aspect of life is sleeping, which is more than just lying on the mattress or bed every night. Our brain becomes more active while we sleep, carrying out tasks such as memory preservation, healing, and hormone regulation that we are unable to focus on enough when we are awake.

REM (rapid eye movement) and NREM (non-rapid eye movement) are the two main sleep stages, distinguished by the brain and body activity, respectively.

What is Non Rapid Eye Movement or NREM?

Non-REM, or non-rapid eye movement, is the first stage of sleep that occurs when we fall asleep on the mattress while still awake. The three stages of non-REM sleep are N1, N2, and N3. Non-REM is made up of light and deep sleep. NREM once had a fourth stage, N4, which is now collectively referred to as N3.

Non-REM Stage 1 or N1 The N1, also known as non-REM stage 1, is the first stage of sleepiness that occurs after a transition from waking and typically lasts for 5 to 10 minutes, or about 5% of the whole sleep cycle. The sleeper might quickly wake up at this stage because it is the lightest slumber.

During this stage:

• Eye movements become sluggish and rolling
• Respiration and heart rate start to become more relaxed
• Muscles start to relax and possibly twitch
• Theta range mixed frequency waves with small magnitudes begin to be produced by the brain

Non-REM Stage 2 or N2

The N2 stage, often referred to as non-REM stage 2, is the second and biggest level of sleepiness that follows the NREM or N1 stage and lasts for 90 to 120 minutes on average, or roughly 45 percent of the sleep cycle. Given the lightness of the sleep, the person might effortlessly wake up.

During this stage:

• You start to become unaware of your surroundings
• Reduced body’s internal temperature
• Eye movements cease
• Heart rate and respiration slow down and become regular.

Non-REM Stage 3 or N3

The N3, or non-REM stage 3, is also known as slow-wave sleep, SWS, or delta sleep. The N3 is the collection of the third and fourth sleepiness stages and the deepest sleep cycle stage. It occurs after NREM 2 stage and lasts for 20 to 40 minutes or about 25% of the sleep cycle. It is the deepest slumber, and the sleeper finds it difficult to wake up even with loud noises. You can wake up feeling rejuvenated and energetic if you receive enough NREM 3 sleep.

During this stage:

• No eye movements, and difficult to awaken from sleep
• Respiration and heartbeat are both at their lowest rates
• Blood pressure decreases, and muscles’ blood flow rises as the body completely relaxes
• Delta brain waves are present, and the brain clears waste
• Cell regeneration, tissue growth, and the production of growth hormones all take place
• Immunological system is strengthened

What is Rapid Eye Movement or REM?

Rapid Eye Movement (REM) sleep is the last stage of the sleep cycle and typically lasts for 20 to 40 minutes, or 25% of the entire sleep cycle. When you are in REM sleep, your brain is more active than when you are awake, while your body is momentarily immobile. You may experience vivid dreams at this point.

• During phasic REM, the eyes move quickly
• Respiration and heartbeat speed up and become more irregular
• Muscles are paralyzed, although they may twitch
• There is an increase in brain activity
• Effective for learning, memory, and problem-solving

To prevent damage during REM sleep caused by dreams acting quickly, it is frequently advised to have a plush or soft mattress.

Each cycle typically travels through the stages of sleep in the following order: wake, light sleep, deep sleep, REM, and repeat. Later cycles have a higher percentage of REM sleep, while cycles early in the night tend to have a deeper sleep. Your body might even decide to forego deep sleep entirely at the end of the cycle.