Sleep Stages: What are they?

Sleep is not a single event. It consists of stages, which combine to form the sleep cycle. They all have a different role to play in making sure we are well rested after sleeping. Ensuring smooth transition between the sleep stages is vital for a good night’s sleep and, by extension for your overall health.

What is the sleep cycle?

The sleep cycle is a process that consists of four separate stages. These all have a role to play and contribute to the quality of our sleep every night. We don’t tend to think about what our sleep consists of. We usually just consider the time we go to bed and when we need to wake up!

We often have unexplained dreams, points when we wake up, and days when our mood is not all that positive. This article is designed to give some insight into why this happens.

Below is the sleep cycle and typically a person will have four to six cycles a night lasting up to 90 minutes each time. The initial cycles will be much shorter and then lengthen in duration as you get to the latter cycles. The cycles consist of two types of sleep functions: non rapid eye movement (NREM) and rapid eye movement (REM) – we’ll be coming back to those two terms later!

sleep cycle diagram sleep stages

What are the Four stages of sleep?


Typically, we associate this stage with ‘drifting off into sleep’. It can last for several minutes and during this stage, you’re not fully asleep. Any slight disturbances can wake a person as the mind and body are not fully relaxed.

This is why at this stage it’s important to have the right environment in terms of noise, temperature, and light. If this is applied, you could expect to fall into stage two of sleep fairly quickly.


This stage is when our body transitions into a more relaxed and subdued state. The muscles will relax the breathing will continue to steady and slow down and so too will your heart rate. To assist with the transition of this stage some would adopt breathing techniques, meditation, or listen to relaxing music to calm the mind and body.

Some would also have a hot or warm shower before bed which brings down your core temperature and slows the circadian rhythm.

As you will have seen, a person can spend at least 50% of their time in N2 sleep roughly lasting 10. 30 minutes per cycle.

NREM Three

Also known as deep sleep is a stage when the body continues to fall into a phase of deep relaxation as the breathing rate and muscle pulses start to decrease. It is much harder to wake someone up in this phase.

Sleep scientists believe that this stage is critical for restorative sleep so that the body can recover, repair and grow both physically and mentally, as brain activity moves into slow-wave sleep. Key benefits you will find during your day from sufficient deep sleep are improved memory and cognitive functioning, as well as a stronger immune system.

You will typically spend 20-40 minutes in deep sleep and then in the later sleep cycles this will decrease and fall more into the REM sleep stages.

the four sleep stages

What can we do to improve the quality of the four stages of sleep?

Create a bedroom environment that supports quality sleep

  • Cool and regulated temperature
  • Dark or ambient lighting
  • Tidy, clean and comfortable room
  • Quiet or relaxing natural sounds

Mind and body relaxation

  • Steading breathing exercises
  • Guided meditation
  • Muscle relation techniques

Sleep-promoting routines

  • Eat and drink two hours before you intend to sleep
  • Limit screen time one hour before bedtime
  • Take time to read a book or magazine before sleep
  • Allow yourself 30 minutes before you want to go to sleep
  • Wear a sleep mask to help block out other light

Better Sleep for Everyone: Tonight’s Challenge

Try and prepare your sleep environment in a way which is comfortable for you and removes technology and any devices. Allow yourself 30 minutes of relaxation before you intend to sleep e.g., if you want to sleep at 10pm then prepare and relax in your bedroom environment from 9.30pm. Give it a go!


  • The sleep cycle is made up of four stages – three non-rapid eye movement stages and one rapid eye movement cycle
  • You could have up to six sleep cycles per night lasting 90 minutes each
  • Sleep stages are the process which helps the mind and body recuperate and regenerate from the day
  • Cycles and the duration of sleep stages are based on factors such as age, routines, alcohol, health conditions, medications, and sleep disorders
  • Improved sleep hygiene can assist with the effectiveness of stage transition