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The 4 stages of sleep

Our nightly sleep consists of four different stages of sleep. All stages occur in a cyclical pattern referred to as one’s sleep architecture. Each sleep stage has its own characteristics and plays an essential role in both our physical and mental well-being. We can distinguish between so-called non-REM (or NREM sleep) and REM sleep. Here’s…

Non-REM sleep

On top of our distinction between REM and non-REM stages of sleep, NREM sleep can further be divided into four different stages of sleep: light sleep, deeper sleep, slow-wave sleep and REM sleep. These stages of sleep are also referred to as N1, N2 and N3 for short. The four stages are determined based on the degree of muscle tone, brain activityand eye movements that occur at each stage. The following characteristics are used to describe the typical sleep cycle.

Stage 1: Light sleep (N1)

During light sleep, your body transitions from wakefulness to a deeper sleep stage. It is quite easy to wake you up during this stage as you still remain somewhat aware of your surroundings. Your muscles begin to relax and your eye movements are minimal. A quiet and comfortable sleeping environment can cause you to quickly move from light sleep to the next stage. This stage of sleep usually lasts less than 10 minutes. Here you can read more about light sleep.

Stage 2: Deep sleep (N2)

Characteristics of deep sleep include decreased muscle tone and significant relaxation. During deep sleep, your body temperature drops and both your heart rate and brain waves slow down. So-called sleep spindles occur during deep sleep. These are bursts of consistent brain activity and are important for learning and forming new memories.

Stage 3: Slow-wave sleep (N3)

Stage 3, or slow-wave sleep (SWS), is the deepest stage of non-REM sleep. Brain activity is at its lowest and produces the slowest brain waves in human beings, known as delta waves. During this time of the night, your body recovers and enhances bone and muscle development. Someone who is in the middle of the SWS sleep stage is usually very difficult to wake up.

REM sleep

REM stands for rapid eye movement and refers to the stage of sleep where vivid
dreaming occurs. During REM sleep, your brain activity is nearly comparable to
wakefulness. The heart rate speeds up as your respiration and blood pressure increase

Sleep duration and affecting factors

The natural sleep cycle is determined as one round consisting of each stage of sleep. You normally go through four to six rounds of the natural sleep cycle every night. The duration of a single sleep cycle varies throughout the night, ranging from 70 to 120 minutes. Your circadian rhythm and sleep cycle can be affected by many factors, such as:

  • Sleeping environment. Environmental factors such as light exposure, night noise, temperature and comfort may affect your sleep stages.
  • Age. Your natural sleep cycle may change as you get older. For example, a newborn baby usually gets more REM sleep than older adults.
  • Lifestyle and routines. Following a balanced lifestyle and healthy eating habits promotes good sleep. Consistent routines can also help fall asleep faster and contribute to a healthier sleep cycle.
  • Stress. High stress levels can affect both your sleep quality and your ability to fall asleep. Stress may have a negative impact on the different stages of sleep and can eventually lead to sleep deprivation.
  • Caffeine and alcohol. A late or excessive caffeine intake disrupts your sleep duration and can lead to trouble falling asleep. Consuming alcohol close to bedtime decreases REM sleep and alters your sleep stages.

Sleep difficulties can lead to excessive tiredness in the daytime, depression, anxiety and besity, among other factors lowering the quality of life. The QuietOn 3.1 noise-canceling earbuds can help you block out external factors disturbing your natural sleep cycles. The active noise-canceling (ANC) technology used in the earbuds helps you fall asleep faster and maintain your healthy sleep habits.

Why do sleep stages matter?

Several important bodily functions are connected with getting enough sleep. It is
important to go through all the different stages of sleep as both physical and mental well-being benefit from healthy sleep habits. Lack of sleep can negatively affect your mood, memory and ability to think clearly. The different sleep stages can further improve your immune system, physical health, recovery and concentration, for example. Getting enough sleep is essentially important for younger people who are still growing as proper sleep promotes growth and hormonal stability. For example, the growth hormone that helps children and teens develop is secreted especially during sleep.