Why is Sleep Important?

Sleep is an active state with increased cerebral blood flow estimated to be 25-80% greater than during wakefulness 1. Getting a sufficient quantity and quality of sleep is therefore essential for optimum physiological and cognitive functioning 2. Poor nocturnal habits can disrupt neuroendocrine function and glucose metabolism, impact negatively on body composition, reduce alertness and decrease immune functioning, all of which may be highly detrimental for the athlete 2,3.

Body Composition


For many sports achieving a low body fat percentage whilst maintaining lean mass is highly desirable from both performance and aesthetic viewpoints. So how does sleep affect body composition?

Firstly, sleep deprivation can lead to increased levels of cortisol. Chronically elevated levels of this stress hormone can wreak havoc on your body, resulting in catabolism (the breaking down of muscle tissue), thyroid gland disruption (crucial to your metabolism), altered blood sugar levels (augmenting the risk of insulin resistance and diabetes), and may also contribute to fat storage around the abdomen (goodbye six-pack!) 4.

Secondly, sleep deprivation can have a major impact on our appetite, reducing the hormone associated with satiety (leptin) and increasing the hormone related to hunger (ghrelin) 3. Despite all the will in the world, sleep deprivation can lead to physiological changes, which can sabotage your best dieting efforts.


Although the literature is inconclusive regarding the impact of sleep deprivation on athletic performance, it is evident that poor sleep patterns do not provide the most favourable conditions for maximizing training efforts or health 2. Good sleeping habits improve immune function, permitting training schedules to be completed free from illness and also facilitate nocturnal growth hormone release, important for the adaptation and recovery from exercise 2,5. Moreover, good sleep patterns may improve learning and memory, assisting the athlete greatly with the cognitive demands inherent across all sporting disciplines 2,6.

athletic performance by Shopie Suri_2

How Much Sleep Do We Need?

Evolving research suggests that there is a lower and an upper threshold for the amount of sleep we need. While our requirements may alter depending on our stage in the life cycle/ life situation, it is generally thought that 7-8 hours per night supports optimum health and wellbeing 7. The quality of our time in bed is equally important with consolidated (i.e. few awakenings) deep sleep (paramount to growth and repair processes) considered most beneficial.

Suggestions to Help Athletes Sleep Soundly The following provides a brief overview on how an athlete can monitor and improve their sleeping patterns:

1. Monitoring your sleep can be useful to provide information about your sleeping patterns. Actigraphy is a way of measuring your body movement (via a wrist watch) during sleep and can provide a good understanding of parameters important to healthy sleep 2. These devices can be purchased in the shops or online. Keeping a diary of how you feel (e.g. excessively tired during the day) or asking your bed partner about your sleep can also be very useful in identifying any negative sleep issues. Seeing your doctor who may refer you for a full sleep study is advised if ongoing sleep problems are not resolving.

2. Busy minds and increased cortisol levels do not lend themselves to a peaceful sleep. Prior to bed, try a short period of meditation or relaxation (without the television or computer) to allow the mind and body to rest and come down from the stresses of the day. Leading sports nutritionist Matt Lovell 8 suggests taking a magnesium supplement/using a magnesium cream or unwinding in an Epsom salt bath before bed to prepare for a calm night. It is advisable to consult your doctor if you have any medical conditions prior to starting a supplementation regime.

3. Your sleeping environment can influence your sleep quality. A dark (light suppresses melatonin release, a hormone influencing the sleep-wake cycle through a sleep promoting effect) quiet room free from mobile phones and laptops etc. is most conducive to a good night’s rest 2. Further, try to establish a regular sleeping routine and consider a blackout blind and wake-up light to keep your internal ‘body clock’ (a biological structure regulating when we sleep/are active) healthy 9.

4. Nutrition in the hours prior to bedtime can affect sleep. The amino acid tryptophan, a precursor to neurotransmitters influencing the sleep cycle is contained in foods such as turkey, salmon and cottage cheese. Try a small low GI carbohydrate (counting the carbohydrates in your macronutrient allowance if you are dieting) and protein mix a few hours prior to bed to take you off to slumber land! 2,8. Also, avoid stimulants in the evening such as caffeine and alcohol as these can disrupt sleep quality.

5. Napping may be highly beneficial for increasing sleep quantity, particularly when training is timetabled into regular early morning slots 2. Napping should take place in the afternoon and last between 10 and 30 minutes in order to promote alertness and improve performance 2,10.


1. Sleep medicine edited by H Smith, CL Comella and B Hogl (2008).

2. Halson SL. Sleep in elite athletes and nutritional interventions to enhance sleep. Sports Med 2014; 44 Suppl 1: S13-23.

3. Leproult R, Van Cauter E. Role of sleep and sleep loss in hormonal release and metabolism. Endocr Dev 2010; 17: 11-21.

4. Cracking the metabolic code by J Lavelle and S Yale (2004).

5. Besedovsky L, Lange T, Born J. Sleep and immune function. Pflugers Arch 2012; 463: 121-137.

6. Walker MP. Cognitive consequences of sleep and sleep loss. Sleep Medicine 2008; 9: S29-S34.

7. Youngstedt SD, Kripke DF. Long sleep and mortality: rationale for sleep restriction. Sleep Med Rev 2004; 8: 159-174.

8. A fist full of food by M Lovell, F Brown and R Klerck (2011).

9. Keeping in time with your body clock by JM Waterhouse, DS Minors, ME Waterhouse, T Reilly and G Atkinson (2002).

10. Dhand R, Sohal H. Good sleep, bad sleep! The role of daytime naps in healthy adults. Curr Opin Pulm Med 2006; 12: 379-382.

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