Sleep influences many aspects of our lives including our physical health and mental wellbeing. But how does sleep impact our performance? In this week’s blog, we discuss the sleep cycle, the impacts of sleep deprivation, and some of the strategies you can use to optimise your sleep and performance.
What happens when we fall asleep?
In order to understand how sleep impacts performance, we need to first take a look at the sleep cycle and how it works. Here are some things to know:
Not all sleep cycles are the same length but one full cycle lasts approximately 90 minutes. On average, you go through five of these cycles in one night (1), with each cycle consisting of non-rapid eye movement (N-REM) sleep and rapid eye movement (REM) sleep (2) (see figure below).
Figure 1: Overview of the Sleep Cycle
Stage 1 (N1):
Just as you start to relax and doze off, have you ever felt like you were floating or falling only to be jolted awake? This is a sudden muscle contraction known as a ‘hypnotic jerk’ which can happen at the beginning of our sleep cycle when we move from wakefulness into a state of sleep (3). During this time, the brain waves start to slow down, muscle activity decreases and eye movement become slower (4).
Stage 2 (N2):
The second stage of sleep represents about 45-55% of total sleep time (5), and is commonly known as ‘light sleep’. During this phase of sleep, the body starts to prepare for deeper rest so our brain wave activity slows down further. Body temperature also drops and heart rate and breathing become more regular.
Stages 3 (N3):
The third stage of sleep also known as ‘deep sleep’ or ‘slow wave sleep’ represents about 20-25% of total sleep time (5). This is the most restorative stage of sleep and is crucial for physical recovery and growth, as well as immune function (6). It is difficult to be woken up from this stage of sleep and if you are woken, the chances are you will wake up groggy, disoriented and probably a little pissed!
**Note: During the first half of the night you spend more time in deep sleep. As the night progresses, the amount of deep sleep tends to decrease and REM sleep becomes longer and more frequent (4,7)
REM:
This is where vivid dreaming happens. Although our brains are highly active during this phase, the body becomes temporarily paralysed while our eyes move rapidly. This stage of sleep is important for brain development, emotional regulation and cognitive function (3,8).
So how do these stages of sleep and their functions contribute to performance?
The final stage of NREM sleep (N3) is crucial for physical recovery. During deep sleep, hormones such as growth hormone are released, which aid with bone growth, muscle growth and development and tissue repair (1). These are necessary processes for athletes to recover following exercise, and are essential for performance and injury prevention. Deep sleep is also important for the immune system. It helps to regulate inflammation in the body, and defend the body against infection and illness (3,6). Finally, REM sleep plays a role in emotional regulation and stress management, which are important factors influencing athletic performance. Adequate REM sleep helps athletes process and cope with stressors related to training, competition, and performance expectations.
‘Am I getting enough sleep?’
It is recommended that adults get a minimum of 7 hours of sleep per night (9), however the amount of sleep you need will vary depending on factors like your age, activity levels and your lifestyle. An important thing to remember about sleep is that it is not just about the quantity but also the quality and timing (i.e. when you go to bed and wake up). Sleeping at the right time ensures that you wake up feeling refreshed and ready to tackle the day ahead.
Irregular sleep times and a lack of quality sleep can affect people in many different ways. Here are some of the signs that you are not getting enough quality sleep:
Fatigue: You may feel tired during the day and that you are lacking energy.
Difficulty concentrating: you are struggling to focus on tasks and/or stay productive throughout the day.
Mood changes: you are feeling more irritable/ emotional than usual and/or are experiencing increased mood swings.
Decreased immune function: you feel ‘run down’. Not getting enough quality sleep can negatively impact your immune system and leave you at risk of getting sick.
Impaired motor skills (particularly for athletes): you may not feel as sharp or co-ordinated, and technical skills that you usually perform with ease become more difficult.
Strategies for Optimising Sleep and Performance
Making small changes to your sleep routine can make a big difference in how you feel and perform during the day. Here are some tips to help you get the most out of your sleep and enhance your athletic performance.
Establish a consistent sleep schedule: try to go to bed and wake up at the same time every day, including weekends.
Create a sleep-friendly environment: keep your room cool and dark. Consider using an eye mask or ear plugs if it is too bright or noisy.
Have a bed-time routine: it is important to give yourself time to wind down before you sleep. Minimise screen time before bed, and instead, engage in activities like reading or listening to soothing music.
Relax your mind: Bedtime is not the time to be thinking about your ‘to-do’ list! To ease bedtime stress, give yourself time during the day to think and reflect.
Mind your intake: Avoid caffeine and heavy meals close to bedtime.
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References:
Nobari, H., Banihashemi, M., Saedmocheshi, S., Prieto-González, P., & Oliveira, R. (2023). Overview of the impact of sleep monitoring on optimal performance, immune system function and injury risk reduction in athletes: A narrative review. Science progress, 106(4), 368504231206265. https://doi.org/10.1177/00368504231206265
Patel AK, Reddy V, Shumway KR, et al. (2024) Physiology, Sleep Stages. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; Available from: https://www.ncbi.nlm.nih.gov/books/NBK526132/
Institute of Medicine (US) Committee on Sleep Medicine and Research; Colten HR, Altevogt BM, editors. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington (DC): National Academies Press (US); 2006. 2, Sleep Physiology. Available from: https://www.ncbi.nlm.nih.gov/books/NBK19956/
Garbarino, S., Lanteri, P., Bragazzi, N. L., Magnavita, N., & Scoditti, E. (2021). Role of sleep deprivation in immune-related disease risk and outcomes. Communications biology, 4(1), 1304. https://doi.org/10.1038/s42003-021-02825-4
Goldstein, A. N., & Walker, M. P. (2014). The role of sleep in emotional brain function. Annual review of clinical psychology, 10, 679–708. https://doi.org/10.1146/annurev-clinpsy-032813-153716
Consensus Conference Panel, Watson NF, Badr MS, Belenky G, Bliwise DL, Buxton OM, Buysse D, Dinges DF, Gangwisch J, Grandner MA, Kushida C. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Journal of Clinical Sleep Medicine. 2015 Jun 15;11(6):591-2.