Most of us know that a good night’s sleep is responsible for a variety of psychological and physiological benefits, but when it comes to sport and fitness, why is sleep so important?
Adequate sleep is crucial for recovery, growth, and repair; whilst sleep deprivation negatively impacts our ability to perform exercise, achieve results, and recover efficiently.
So, just how does sleep affect physical performance and training?
Our Sleep Cycle
According to a study by Marshall and Turner (1) ‘Sleep is an influential factor that affects the quality of training, given its implications on the recovery process.’
We have five sleep states in our sleep cycle.
1-4 – Non REM sleep
5 – REM sleep – our most ‘active’ sleep state, otherwise known as rapid-eye-movement.
Stages 3-4 of this cycle are when we sleep deepest. This is when our body goes through most of its recovery.
Our body will then revert to earlier stages, before progressing to REM and repeating the cycle.
According to research, ‘A greater frequency and duration of REM experienced during total sleep is suggested to enhance recovery processes and lead to more optimal wakefulness (2).
Therefore, achieving deeper phases of sleep, more often, will promote greater recovery and energy.
Sleep Cycles and Our Systems
Many processes are at work whilst we sleep, contributing to recovery, repair, and growth, amongst other physical and mental benefits.
Hormone Regulation
During stages 3-4 of sleep, two hormones are released.
Melatonin
Melatonin acts as an antioxidant, improving our immune systems and also regulating our circadian rhythms (our internal body clocks.)
Growth Hormone
The growth hormone aids muscle repair, helps build muscle, improves bone strength, and encourages fat oxidisation (3).
Therefore, deep sleep will provide a greater chance for muscle growth.
System Reboot!
Sleep helps to protect our immune, endocrine, nervous and metabolic system, whilst stimulating memory and learning potential (4).
Across various studies, efficient sleep has also been found to improve motivation,
reduce inflammation, decrease fatigue, and decrease stress.
We are therefore less likely to over-train or suffer an injury; improving performance and ability.
The Effects Of Sleep Deprivation
It is recommended that we average 7-9 hours of sleep per night.
However, for athletes (and those of us engaging in more frequent and/or intense physical exercise), this could be more, as our bodies need time to counteract the stress of training.
Research suggests (5) that sleep deprivation decreases the time in which exhaustion is reached.
Hormonal and metabolic changes were also observed- including decreased glucose tolerance and increased insulin resistance, meaning our growth hormone may have less time to ‘mediate’ Carbohydrate metabolism, and potentially decreases the supply of energy to muscles.
Our Top Tip?
Sleep and physical training share a symbiotic relationship, which is to say, one directly affects the other. Always aim to get at least 7 hours of quality sleep per night, allowing your body plenty of recovery.
The content of this article does not constitute medical advice by a registered healthcare professional. Please consult your physician before starting any new diet, exercise or training programme.
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References
- Marshall, Geoff J.G. MSc, CSCS; Turner, Anthony N. MSc, CSCS*D, ‘The Importance of Sleep for Athletic Performance’, Strength and Conditioning Journal: February 2016 – Volume 38 – Issue 1 – p 61-67 doi: 10.1519/SSC.0000000000000189 < https://journals.lww.com/nsca-scj/Fulltext/2016/02000/The_Importance_of_Sleep_for_Athletic_Performance.9.aspx>
- 43. Walters PH. Sleep, the athlete and performance. Strength and Conditioning J 32: 17-24,2002.
- Marshall, Geoff J.G. MSc, CSCS; Turner, Anthony N. MSc, CSCS*D, ‘The Importance of Sleep for Athletic Performance’, Strength and Conditioning Journal: February 2016 – Volume 38 – Issue 1 – p 61-67 doi: 10.1519/SSC.0000000000000189 < https://journals.lww.com/nsca-scj/Fulltext/2016/02000/The_Importance_of_Sleep_for_Athletic_Performance.9.aspx>
- Doherty R, Madigan S, Warrington G, Ellis J. Sleep and Nutrition Interactions: Implications for Athletes. Nutrients. 2019;11(4):822. Published 2019 Apr 11. doi:10.3390/nu11040822
- VanHelder T, Radomski MW. Sleep deprivation and the effect on exercise performance. Sports Med. 1989 Apr;7(4):235-47. doi: 10.2165/00007256-198907040-00002. PMID: 2657963.
