The 5 stages of sleep: everything you need to know

August 5, 2020 5 mins read
The 5 stages of sleep: everything you need to know

There are 5 stages of sleep, consisting of both rapid eye movement (REM) and non-REM sleep that we cycle through each night. The average person spends around a third of their life asleep, so by understanding our sleep cycles and sleep stages, we can start to see why sleep plays such an important role in our health and wellness.

In this article, we cover the 5 stages of sleep that help our bodies replenish energy stores and make repairs, all while our minds organize and store the memories of the day before.

What are the different stages of sleep?

Within the 5 stages of sleep are two types of sleep cycles that play a vital role. REM and non-REM sleep. The non-REM sleep phase is made up of multiple stages; falling asleep, light sleep and slow-wave deep sleep, which is the linking stage between non-REM and REM sleep. REM or dream sleep makes up the final and single stage of each 90-minute sleep cycle.

Stage 1 – falling asleep

The first stage is one of the shortest as we prepare ourselves to transition into a sleep state. In this stage, the mind and body begin to slow down as we start to float in and out of consciousness, causing us to feel drowsy and relaxed as we fall asleep.

Stage attributes:

Stage 2 – light sleep

This next stage of non-REM sleep is a period of light sleep before you enter deep sleep. Almost 50% of the time spent asleep over the course of the night is spent in stage 2. During this stage, the brain produces sudden spikes in brainwaves known as sleep spindles (named after their spindly appearance on EEG charts.) These spikes in brain activity are thought to play a role in long-term memory consolidation and sensory processing, making this an important stage as we age.

Stage attributes:

  • Further slowing down of breathing and heartbeat
  • Limited eye movements
  • A decrease in body temperature
  • Production of “sleep spindles” (a spike in our brainwaves)

Stage 3 and 4 – slow-wave sleep

These final stages of non-REM sleep are the deepest sleep stages and become much more difficult to wake from. Stages 3 and 4 are known as slow-wave sleep attributing to the slow delta brainwaves occurring during this stage. This stage is also where your body performs a variety of important health-promoting and recovery tasks.

Stage attributes:

  • Difficult to wake from
  • Slow heartbeat and breathing
  • Limited to no eye movements
  • The body is in a completely relaxed state
  • The occurrence of delta brain waves
  • Tissue repair
  • Regeneration of cells
  • Strengthening of the immune system

Stage 5 – REM sleep

The final stage of the sleep cycle is the REM phase (dream sleep). REM sleep plays a vital role in the brain’s ability to learn and remember since it is during REM sleep that the brain processes, consolidates, and stores information into our long-term memory banks. These neurological and physiological responses play a similar role to being awake and are also where we experience most of our dreams as our brain activity increases to perform these neurological responses.

Stage attributes:

  • Rapid eye movements
  • Increase in breathing and heart rate
  • Temporary paralysis of limb muscles with some occasional twitches
  • Hyper increase in brain activity

How long is a sleep cycle?

Each sleep cycle lasts around 90 minutes, and to feel fully rested and refreshed when we wake up, we must experience all 5 stages of sleep. A full night’s sleep will include five or six cycles, whilst a disturbed, restless night will consist of fewer. During these sleep cycles, our breathing, heart rate, muscles, and brainwaves are all affected differently, allowing our bodies to find full rejuvenation at each stage.

It’s also important to ensure that you schedule specific wake-up times as this will ensure the brain wakes up at an appropriate stage in its sleep cycle. Ideally, our circadian rhythm will climb in the morning and make us feel alert and refreshed, and this can only be fully experienced if we’ve kept to a consistent sleep routine and introduced good sleeping hygiene habits into our evening rituals.

What a full sleep cycle in timed intervals looks like:

  • Stage 1 (falling asleep): 5-10 minutes. The body starts to relax and succumb to sleep.
  • Stage 2 (light sleep): 25 minutes. This stage is the easiest to wake up from. Power napping in this stage is ideal and shouldn’t be more than 30 minutes long, as it allows your body to transition from stage 1 to 2 and get the benefits of full rest.
  • Stages 3 and 4 (slow-wave sleep): 60 minutes. This is the repair stage of our sleep, where the body begins its restoring process. It’s important to note that waking up during this deep sleep will likely lead to sleep inertia which causes one to feel groggy.
  • Stage 5 (REM sleep): 10 minutes. This stage occurs about 90 minutes after you fall asleep, and as we’ve explored, is the primary dreaming stage of sleep. REM sleep lasts roughly 10 minutes the first time, increasing with each REM cycle. The final cycle of REM sleep usually lasts for roughly 60 minutes.

Getting enough sleep is important for health-promoting activities such as digestion, growth, and memory. By understanding our stages of sleep, which can be further explored by using a sleep monitor, we can see how important it is to get a good night’s rest, and the role it plays for our mind, body and soul’s overall wellbeing.