When we are busy, when we have deadlines to meet or goals to achieve, sleep is often disregarded and neglected. A culture of sleep deprivation and a negative attitude towards sleep has pervaded, with over 30% of adults aged 30-65 sleeping less than 6 hours a night [1]. However, the scientific literature points in the opposite direction, with sleep quality having a key influence on cognitive ability, motor memory, metabolism, immune function, and mental health. Moreover, it has been found to have a direct impact on athletic performance, and susceptibility to injury.
How sleep deprivation impacts the body?
Many people assume that the only consequence of poor sleep is day-time sleepiness, resulting in a minor cognitive deficits. It is true that cognitive deficits are a problem, with an estimated 10-15% of fatal road crashes due to driver fatigue, and 100,000 deaths in US hospitals due to medical errors as a result of sleep deprivation [2].
However, sleep also has many other effects on the body.
- In many studies, levels of white blood cells and antibodies in the blood have been found to drop, sometimes by as much as 80%, weakening the immune system and increasing susceptibility to illness [3].
- Obesity is linked to short sleep, due to elevated ghrelin (the ‘hunger hormone’) and decreased leptin (which signals satiety) [4].
- Sleep deprivation has also been found to impact risk of coronary heart disease and hypertension, with a 45% higher risk of fatal heart attack for someone that regularly sleeps less than 5 hours a night [5].
- Remarkably, the brain mechanisms underlying sleep, such as the serotonergic system, have been implicated with mental health disorders including depression and schizophrenia as well as neurodegenerative diseases [6].
Clearly, sleep disturbance has a much more significant impact than many people might imagine.
Sleep and athletic performance
Increasing numbers of studies are finding direct associations between sleep and exercise performance.
- A study at Stanford University found that extending sleep of collegiate basketball players by an average of 110 minutes for 5-7 weeks improved sprint times, shooting accuracy, reaction time and mood [7], and another study found that partial sleep deprivation had significant effects on weight lifting performance after just two nights of low sleep [8]. Endurance performance has been found to be affected after lack of sleep [9].
- Emotional well-being is particularly susceptible to sleep quality and with sleep deprivation leading not only to disruption of mood states but also increased pain perception [10].
- Reduced injury rates are also associated with sleep quality: Sleep deprivation is a strong predictor of injury in adolescent athletes, highlighting the risk of over scheduling and leaving inadequate time for rest and recovery between training or competitions [11,12]. One study even suggests that poor sleep quality can result in autonomic nervous system imbalance, simulating symptoms of overtraining [13].
Sleep is a key component for physiological, biochemical, and cognitive restoration and recovery.
In addition to this, improvements in motor skill performance following practice are boosted by sleep, with a study finding a 20% increase in motor speed, without loss of accuracy after a night of sleep compared to an equivalent time awake. Indeed, with the sleep-dependent modulation of long-term synaptic plasticity providing a possible explanation for the gains in athletic and motor performance.
How to sleep better
There is a plethora of information provided by clinicians and scientists regarding managing and improving sleep; some key points are outlined here. The use of sleep hygiene practices has been found to be an important predictor of sleep quality[15]. These include sleeping and waking at regular times in order to match the body’s circadian rhythms, ensuring that this includes sufficient sleep (>7 hours, and preferably 8-9 hours in the periods of high training volume or during tapering for important events), and reducing light levels in the evenings. Since sleep onset is associated with falling body temperature, and warming the skin, for example with a warm shower, has been found to increase loss of heat from the skin, helping to induce sleep [10].
Avoiding alcohol and caffeine is also important. Caffeine is a well-known negative influence on sleep quality due to its action as a stimulant, and should be avoided in the late afternoon and evening.
Alcohol is often seen as a sleep promoter, but despite promoting the onset of sleep, it interferes with sleep quality by reducing the quantity of REM sleep at the beginning of sleep, and later resulting in frequent waking, thus resulting in increased fatigue [10].
Napping can improve cognitive performance and reduce sleepiness, however it is typically recommended not to nap for longer than 45 minutes so as not to induce further sleepiness [10].
Wattson Blue and Sleep
Although it can be beneficial to use wearables or one of the available mobile apps to track your sleep, it has been suggested that self-reported measures of sleep duration show a very large positive correlation (r=0.85) to actual sleep durations[16]. This makes Wattson Blue an excellent non-invasive tool for tracking sleep.
This makes Wattson Blue an excellent non-invasive tool for tracking sleep.
Every morning that you use Wattson Blue, you answer two questions about your sleep quality and duration, allowing you to reflect on the quality of your recovery from the day before. Over time, you can see how sleep affects your personal performance, mood and other metrics such as HRV (chronic sleep deprivation has been found to reduce heart rate variability [17]), helping you to adjust your training and improve outcomes.
Wattson Blue athletes on average slept 25 minutes longer than the same period a year earlier
Over the past 4 months, Wattson Blue athletes have slept on average of 8 hours a night, although many of our top athletes generally sleep longer than this. Moreover, we have found that improved feedback within the app has led to an increase in average sleep duration: Over the past 4 months Wattson Blue athletes on average slept 25 minutes longer than the same period a year earlier.
Download Wattson Blue today, and start tracking your sleep and other recovery metrics today.
Further Reading
Harvard Healthy Sleep: Twelve Simple Tips to Improve Your Sleep
Why We Sleep: Unlocking the Power of Sleep and Dreams, Matthew Walker (book)
References
1 Institute of Medicine. (2006). Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington, DC: The National Academies Press. https://doi.org/10.17226/11617
2 Ferrie JE, Kumari M, Salo P, Singh-Manoux A, Kivimäki M. (2011). Sleep epidemiology – a rapidly growing field. International Journal of Epidemiology, 40(6): 1431–1437. http://doi.org/10.1093/ije/dyr203
3 Bryant PA, Trinder J, Curtis N. (2004). Sick and tired: does sleep have a vital role in the immune system? Nature Reviews Immunology, 4: 457–467. https://doi.org/10.1038/nri1369
4 Taheri S, Lin L, Austin D, Young T, Mignot E. (2004). Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. PLOS Medicine. https://doi.org/10.1371/journal.pmed.0010062
5 Imeri L, Opp MR. (2009). How (and why) the immune system makes us sleep. Nature Reviews Neuroscience, 10: 199–210. https://doi.org/10.1038/nrn2576
6 Wulff K, Gatti S, Wettstein JG, Foster RG. (2010). Sleep and circadian rhythm disruption in psychiatric and neurodegenerative disease. Nature Reviews Neuroscience, 11: 589–599. https://doi.org/10.1038/nrn2868
7 Cheri D. Mah, Kenneth E. Mah, Eric J. Kezirian, William C. Dement. (2011). The Effects of Sleep Extension on the Athletic Performance of Collegiate Basketball Players. Sleep, 34(7): 943–950. https://doi.org/10.5665/sleep.1132
8 Reilly T, Piercy M. (2007). The effect of partial sleep deprivation on weight-lifting performance. Ergonomics, 37(1): 107-115 https://doi.org/10.1080/00140139408963628
9 Oliver SJ, Costa RJS, Laing SJ, et al. (2009). One night of sleep deprivation decreases treadmill endurance performance. Eur J Appl Phsyiol, 107: 155. https://doi.org/10.1007/s00421-009-1103-9
10 Halson SL. Nutrition, sleep and recovery. European Journal of Sport Science, 8(2): 119-126 https://doi.org/10.1080/17461390801954794
11 Milewski MD, Skaggs DL, Bishop GA, Pace JL Ibrahim DA, Wren TAL, Barzdukas A. (2014). Chronic Lack of Sleep is Associated With Increased Sports Injuries in Adolescent Athletes. Journal of Pediatric Orthopaedics, 34(2): 129-133. https://doi.org/10.1097/BPO.0000000000000151
12 Luke A, Lazaro RM, Bergeron MF, Keyser L, Benjamin H, Brenner J, d’Hemecourt P, Grady M, Philpott J, Smith A. (2011). Sports-Related Injuries in Youth Athletes: Is Overscheduling a Risk factor? Clinical Journal of Sport Medicine, 21(4): 307-314 https://doi.org/10.1097/JSM.0b013e3182218f71
13 Fullagar HHK, Skorski S, Duffield R, et al. (2015). Sleep and Athletic Performance: The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise. Sports Med, 45: 161. https://doi.org/10.1007/s40279-014-0260-0
14 Walker MP, Brakefield T, Morgan A, Hobson JA, Stickgold R. (2002). Practice with Sleep Makes Perfect. Neuron, 35(1): 205-211. https://doi.org/10.1016/S0896-6273(02)00746-8
15 LeBourgeois MK, Giannotti F, Cortesi F, Wolfson AR, Harsh J. (2005). The Relationship Between Reported Sleep Quality and Sleep Hygiene in Italian and American Adolescents. Pediatrics, 115: 257-265 https://doi.org/10.1542/peds.2004-0815H
16 O’Donnell S, Beaven CM, Driller MW (2018). From pillow to podium: a review on understanding sleep for elite athletes. Nat Sci Sleep. 2018; 10: 243–253. 10.2147/NSS.S158598
17 Takase B, Akima T, Satomura, Fumitaka, Ohsuzu, Mastui T, Ishihara M, Kurita A. (2005). Effects of chronic sleep deprivation on autonomic activity by examining heart rate variability, plasma catecholamine, and intracellular magnesium levels. Biomedicine & Pharmacotherapy, 58: S35-S39. https://doi.org/10.1016/S0753-3322(04)80007-6