How long is a sleep cycle? The four stages of a healthy cycle…

How long is a sleep cycle? The four stages of a healthy cycle…

In this simple guide you will get to grips with the basics of the sleep cycle. Including what stages we go through, how they affect our minds and bodies as well as what happens if you have an unhealthy cycle.

Navigate through the post by clicking on a topic:

  1. What is a sleep cycle?
  2. How long does each stage last?
  3. How many cycles do we go through each night?
  4. What part of the brain controls the sleep wake cycle?
  5. When do you dream during the cycle?
  6. What does a healthy sleep cycle look like?
  7. What is the best stage to wake up in?
  8. Which is the most important stage?

But first, let’s start with a definition…


What is a sleep cycle?

In short, the sleep cycle is the process your brain and body goes through to repair and restore your physical and mental state when you’re asleep. It consists of these 4 stages:

  1. Initial light sleep – Your eyes close and you begin to drift off. You can very easily be woken in this phase.
  2. Further light sleep – You can still easily be woken, but your brain and body begins to prepare for the deep stage.
  3. Deep sleep – It is very difficult to wake somebody in this phase. The brain switches off, muscle tissue is repaired, and energy is built up for the following day.
  4. REM – Intense brain activity begins as you begin to dream. Eyes are closed but they rapidly move from side to side. This phase processes and stores memories and emotions.

Here is a more scientific definition from Wikipedia:

Now you’re aware of the four stages, let’s take a look at how long each one lasts…


How long does each sleep cycle last?

Here’s a simple break down of roughly how long each stage lasts in the cycle:

Stage 1 Light: 5 to 10 minutes.

Stage 2 Light: 20 minutes.

Stage 3 Deep: 1.5 to 1.8 hours.

Stage 4 REM: 10 minutes to 1 hour.

It’s important to be aware that the duration of each phase can vary a lot from person to person. It depends on various factors such as their personal characteristics, health, sleep habits and routines etc.

When looking at what percentages each stage takes up of the cycle, this guide shows you how it’s broken up:

Stages 1 and 2 Light: 50%.

Stage 3 Deep: 25%.

Stage 4 REM: 25%.

You may add up these time frames and come to the conclusion that they don’t equate to the average 7 – 9 hours of sleep we need every night.

That’s because we experience multiple cycles throughout the night…


How many sleep cycles do we go through each night?

We go through at least 4 or 5 cycles every night. This is the recommended amount to feel energised and fresh when you wake up, so any less than this may cause you to feel tired and groggy.

In the first few cycles, we spend longer in the third stage, deep sleep. This is because our bodies prioritise the restoration of muscle tissue and cellular repair.

Once your body has completed the necessary restoration, this phase becomes shorter.

This allows for more time for stages 1, 2 and 3 in the later cycles. This offers an explanation as to why dreams seem to be longer towards the end of your cycle rather than when you first fall asleep.

Keep reading to find out which part of the brain controls these cycles…


What part of the brain controls the sleep wake cycle?

The hypothalamus is the region of the brain that is responsible for our sleep wake cycles. Specifically, the neurons called ventrolateral preoptic nucleus (VLPO) in the hypothalamus control the transition into sleep.

The VLPO connect directly to the brain’s arousal centres. During the day, the VLPO will stimulate the arousal centre and create brain activity. At night, they restrict activity in the arousal centres by sending neuron signals.

By prohibiting stimulation in these areas, the brain transitions into the sleep cycle.

Keep reading to find out more about the brain’s activity during the sleep cycle and in which stage dreaming takes place…


When do you dream during the sleep cycle?

Dreaming mainly takes place in the fourth stage, REM. Although, it can sometimes take place in the stage 1 or 2, the lighter stages.

It usually never takes place in the third stage, deep sleep. This is because deep sleep focuses on restoration of the body, and brain activity is minimal in this stage.

In REM, brain activity is high, and this stage is used to process emotions and memories. This is when we begin to dream, and the brain temporarily paralyses the arms and legs to prevent movement or reactions from the dreams.

This is where the fourth stage coined its title, REM. It stands for rapid eye movement, which is what happens when we are dreaming or experiencing high brain activity.

Dreaming during the REM or light stage is evidence of a healthy sleep cycle. Here are some more indicators as to whether your cycle is how it should be…


What does a healthy sleep cycle look like?

This pie chart gives you a general idea of what a healthy cycle looks like. Although, it is difficult to give exact figures as not only does everyone have varying cycles, but the length of each stage changes throughout the night.

Here are a few benefits of a healthy cycle:

  • Concentration and productivity is improved
  • Athletic performance is improved
  • Immune system is strengthened
  • Memory is improved
  • Inflammation is reduced
  • Creativity is increased
  • Stress is reduced

Waking up in the correct phase is also key to feeling happy, alert and refreshed…


The best sleep cycle to wake up in so you feel energised and refreshed…

The best stage to wake up in is the light stage. This is because you aren’t in deep sleep, so you won’t feel groggy or confused when waking up in this stage.

The worst stage to wake up in is deep sleep. If you wake up feeling tired, groggy, confused or disorientated, it may be because you have just woken up from a phase of deep sleep.

Waking up during the REM stage is also not ideal, as this can also lead to confusion and disorientation due to the dream-like state you were in. Some people still think they are dreaming when they wake up in this stage, or even experience sleep paralysis.

Our brains temporarily paralyse our arms and legs during REM to prevent movement or reactions from the dreams we experience, which can lead to continued temporary paralysis when we wake up in this stage.

If you’re struggling to wake up in the light stage, there are plenty of apps and tools available to train your mind and body into this healthy cycle.

Although the light stage is ideal for waking up in, it isn’t the most beneficial or restorative. Keep reading to find out which is the most important…


Which sleep cycle is most important?

For the restoration of our bodies and repairment of muscle tissue, stage 3 (deep sleep) is the most important phase.

This allows our bodies to fully recover from the day and carry out cellular repair. It also builds our energy up for the next day, so we feel refreshed and energised in the morning.

If you don’t get enough of this crucial phase, it could lead to premature ageing, severe fatigue, weakened immune system, emotional issues, weight gain and other detrimental symptoms.


Maintaining a healthy sleep cycle with the Siesta in Style blog…

We created the Siesta in Style blog to help readers improve the quality of their sleep.

Our core mission is to provide education and insight into the science behind sleep, so that you can improve your nightly routine and feel better the next day.

Take a look at our other posts here, and please feel free to leave any questions or suggestions in the comment section below.

Back to blog