Science

Sleep Stages

18.03.2022 3 minute read

When we think about getting the right amount of sleep, we generally focus on how many hours of sleep, but what we mustn’t neglect is the quality of sleep we are getting too. The main aim of sleep is restoration which we achieve through cycling through each segment of the sleep cycle. 


What Are the Sleep Stages? 


Composed of four separate stages, each has a unique function and role in maintaining your brain's overall cognitive performance. Some stages are also associated with physical repairs that contribute to overall health and set you up for the next day! There are four sleep stages, all determined by our brain activity during sleep. One for rapid eye movement (REM) sleep and three that form non-REM (NREM) sleep. 


Stage 1- the “dozing off” 


At this early sleep stage, typically lasting one to five minutes, brain activity has started to slow with periods of short movements which may present as those “twitches” as you fall asleep. The body hasn’t fully relaxed yet but its starting to wind down. 


Stage 2- “Light sleep”


According to the American Sleep Foundation, people spend around 50% of their total sleep time during NREM stage 2, which typically lasts for about 20-30 minutes per cycle. Your body starts to become less aware of your surroundings and your breathing and heart rate become slower and more regular. The brain also starts to produce bursts of rapid brain wave activity, known as “sleep spindles”. These “spindles”, are thought to be part of memory formations and consolidation, processing all the new memories acquired the previous day.


Stage 3 - “Deep Sleep”


The most critical stage of the sleep cycle, leading to the most effective restorative sleep, allowing for bodily recovery and growth. Stage 3 sleep is also known as deep sleep, and it is the hardest stage to wake someone up. At this stage, your muscles are completely relaxed and your blood pressure drops and breathing slows. We spend the most time in this deep sleep, commonly lasting for 20-40 minutes. Getting enough NREM stage 3 sleep allows you to feel refreshed the next day.


Stage 4 - "REM Sleep"

REM sleep begins approximately 90 minutes after falling asleep and counts for around 25% of sleep in adults. At this time our brain lights up with activity, similar to when we are awake. REM sleep is key for concreting essential cognitive functions such as like memory, learning, and creativity. REM sleep is also known for the most vivid dreams.


How Can You Have a Healthier Sleep Cycle?

Seven to nine hours of sleep per night isn't the only important factor when assessing your sleep, we must ensure it's uninterrupted, quality sleep that allows your body to benefit from each of these four stages.


While we don’t always have full control of our sleep cycle, there's definitely steps we can take to try improve our sleep quality and length.


  • Sleep hygiene- our sleep environment 

  • Time to splash out on the best mattress, best pillows, and best sheets. Comfort and environment are key. Create a haven for when you rest you head. 


  • Sleep Habits- create routine

  •  Achieving a more consistent sleep schedule, getting natural daylight exposure, avoiding alcohol before bedtime, and eliminating noise and light disruptions can help you get uninterrupted sleep and promote proper alignment of your circadian rhythm.


  • Daily movement = more ZZZ’s 

  • Include physical activity in your daily routine which will, in turn, improve your sleep quality. Regular physical activity, especially outdoor activity, can promote better sleep. Perhaps swap your afternoon Instagram scroll for a 30-minute brisk walk in the fresh air. 



    Mednick, Sara C. “REM, not incubation, improves creativity by priming associative networks.” PubMed, 23 June 2009, https://pubmed.ncbi.nlm.nih.gov/19506253/. Accessed 18 March 2022.

    Mind. “Brain Basics: Understanding Sleep.” National Institute of Neurological Disorders and Stroke, 13 August 2019, https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep. Accessed 18 March 2022.

    National Institute of Neurological Disorders and Stroke. “Brain Basics: Understanding Sleep.” National Institute of Neurological Disorders and Stroke, 13 August 2019, https://www.ninds.nih.gov/Disorders/patient-caregiver-education/understanding-sleep. Accessed 18 March 2022.

    sleep foundation. “How Much Sleep Do We Really Need?” Sleep Foundation, 10 March 2021, https://www.sleepfoundation.org/how-sleep-works/how-much-sleep-do-we-really-need. Accessed 18 March 2022.

    “Stages of Sleep: What Happens in a Sleep Cycle.” Sleep Foundation, 20 December 2021, https://www.sleepfoundation.org/stages-of-sleep. Accessed 18 March 2022.