When we sleep, our bodies undergo various cycles and stages commonly referred to as “sleep architecture.”^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} Your sleep architecture helps regulate your body’s internal “clock”, which controls the production of melatonin – the sleep hormone that makes you feel sleepy.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} During sleep, your melatonin levels rise sharply.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} Over the course of the night, your total sleep is made up of several rounds of the sleep cycle, which is composed of four stages.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} While sleep isn’t uniform, most people typically go through 4-6 of these cycles lasting about 90 minutes each.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.}

During sleep, your brain can process information, consolidate memory, and enable you to learn and function effectively during daytime.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} Four stages make up each sleep-wake cycle.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep. 3Minkoff K. Sleep: The Evolution of Sleep Medicine in Neurology (Part One). OAJNN 2016;2(1):7-8.} One stage is for rapid eye movement (REM) sleep and the others are for non-REM (NREM) sleep.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep. 3Minkoff K. Sleep: The Evolution of Sleep Medicine in Neurology (Part One). OAJNN 2016;2(1):7-8.} It is important to undergo each sleep stage in each sleep-wake cycle, as they allow the brain and the body to recuperate and develop.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.}

This stage is the bridge between being awake and sleep.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} You drift in and out of light sleep during this stage and can be woken up easily.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} It is during this stage that you begin to breathe more slowly and evenly which also slows down your muscle activity.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} You might twitch because of this and sometimes even be woken up by a particularly hard jerk accompanied by the sensation of falling.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.}

After a few minutes in NREM Stage 1, you pass into NREM Stage 2 – another form of light sleep.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} Your breathing pattern slows down further and your heart rate slows down as well.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} You become less aware of the outside world, but will not feel as if you have been sleeping should you be woken.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} This stage accounts for the largest part of human sleep and is sometimes referred to as true sleep.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.}

Also known as deep sleep, it is harder for you to be woken up when you enter into NREM Stage 3.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} Your breathing pattern and heart rate slow down further, and your muscle tones also relaxes.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} This stage is critical for restorative sleep, as it allows for bodily recovery and growth.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} It may also bolster the immune system and other key bodily processes.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} Even though brain activity is reduced, there is evidence that deep sleep contributes to insightful thinking, creativity, and memory.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.}

As you can, sleep is a much more complex process than many people realise, but it is crucial to your health.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} The link between sleep and health is two way.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.} Your sleep shouldn’t be treated as an inconvenience and should be taken seriously.^{2Robotham D, Chakkalackal L, Cyhlarova E. Sleep matters: The impact of sleep on health and wellbeing. London, UK: Mental Health Foundation. 2011.}

Your brain activity picks up during REM sleep, nearing levels seen when you’re awake.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} Your body also experiences a temporary paralysis of the muscles with the exception of the muscles in your eyes and the muscles that control your breathing.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.} REM sleep is crucial for cognitive functions and is known for the most vivid dreams.^{1Suni E. Stages of Sleep. online 2022. cited Apr 2022. URL: Available: https://www.sleepfoundation.org/stages-of-sleep.}