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113_halson_sse.pdfSports Science Exchange (2013) Vol. 26, No. 113, 1-4 SLEEP AND THE ELITE ATHLETE
Shona L. Halson | Recovery Center | Australian Institute of Sport | Canberra | Australia
Sleep is essential for athletes, both for preparing for, and recovering from, training and competition.
Sleep disturbances in elite athletes can occur both during training and following competition.
Sub-maximal, prolonged exercise appears to be more affected by sleep deprivation than short, maximal efforts.
Sleep extension and napping can be effective means of enhancing performance in athletes.
Athletes should focus on utilizing good sleep hygiene to improve sleep and potentially athletic performance.
characterised by muscle atonia (lack of normal muscle tension), bursts of rapid eye movement and dreaming. Therefore, REM sleep Although the function of sleep is not ful y understood, it is general y is considered an activated brain in a paralyzed body. accepted that it serves to recover from previous wakefulness and/or prepare for functioning in the subsequent wake period. An individual’s recent sleep history therefore has a marked impact on their daytime functioning. Restricting sleep to less than 6 h per night for four or more consecutive nights has been shown to impair cognitive performance and mood (Belenky et al., 2003), disturb glucose metabolism (Spiegel et al., 1999), appetite regulation (Spiegel et al., 2004) and immune function (Krueger et al., 2011). This type of evidence has led to the recommendation that adults should obtain 8 h of sleep per night to prevent neurobehavioual While there is considerable data available related to the amount of sleep obtained by adults in the general population, there are few Figure 1. The progression of sleep stages across a single night in a normal
published data related to the amount of sleep obtained by elite young adult volunteer is illustrated in this sleep histogram. The text describes
athletes. This appears to be a considerable oversight given that the ideal or average pattern (Carskadon & Dement, 2011).
sleep has been recognized as an essential component of preparation for, and recovery from high-intensity training (Reilly & Edwards, 2007; Robson-Ansley et al., 2009; Samuels, 2008). Recently it has been hypothesized that sleep and in particular slow-wave sleep (SWS, or deep sleep), is important for recovery in athletes. SWS consists of stages 3 and 4 of NREM sleep. Evidence in support of this theory includes the synchrony of growth hormone release with SWS in humans, the suggestion that optimum conditions for Sleep can be defined as a reversible behavioural state where an anabolism prevail during sleep, and studies showing SWS duration individual is perceptually disengaged from and unresponsive to to be proportional to preceding wakefulness (Shapiro et al., 1981). the environment (Carskadon & Dement, 2011). Sleep is a complex physiological and behavioural state which has two primary states Shapiro et al. (1981) investigated sleep prior to and following a 92 based on physiological parameters. These are rapid eye movement km marathon in six subjects. Results indicated total sleep time (REM) and non-REM (NREM) stages. An electroencephalogram increased significantly over control times on each of the four nights (EEG) where electrodes measure brain electrical activity is used after the marathon. Wakefulness was greatest on the night of the to identify the two states (Figure 1). NREM sleep is divided into marathon, suggested to be related to muscle pain. The percentage four stages (1-4) and is associated with a progressive increase of SWS increased on both nights 1 and 2. The quantitative increase in the depth of sleep (Carskadon & Dement, 2011). REM sleep is in total sleep time and particularly in SWS and the qualitative shift Sports Science Exchange (2013) Vol. 26, No. 113, 1-4 toward more stage 4 sleep immediately after metabolic stress and total volume load and training intensity) following 24 h of sleep supports the theory that sleep (particularly SWS) is important for deprivation when compared to no sleep deprivation (Blumert et al., 2007). However, mood state as assessed by the Profile of Mood States was significantly altered, with confusion, vigour, fatigue and total mood disturbance all negatively affected by sleep deprivation. There are two commonly used methods to assess sleep, Actigraphy and Polysomnography. Actigraphy is a non-invasive method of While much of the research has focused on anaerobic monitoring sleep and involves wearing wrist activity monitors, which performance, reductions in endurance running performance are devices worn like a wristwatch that continuously record body have been observed following 24 h of sleep deprivation (Oliver movement (usual y stored in 1-min epochs). Sleep diaries are also et al., 2009). Interestingly, this occurred without any changes in collected where participants record the start and end date/time for physiological parameters and pacing.
all sleep periods (i.e., night-time sleeps and daytime naps). Data from sleep diaries and activity monitors are used to determine when The mechanism behind the reduced performance following participants are awake and when they are asleep. Essentially, all prolonged sustained sleep deprivation is not clear; however, it time is scored as wake unless (i) the sleep diary indicates that the has been suggested that an increased perception of effort is one participant was lying down attempting to sleep, and (ii) the activity potential cause. While the above studies provide some insight counts from the monitor are sufficiently low to indicate that the into the relationship between sleep deprivation and performance, participant was immobile. When these two conditions are satisfied most athletes are more likely to experience acute bouts of partial simultaneously, time is scored as sleep. Actigraphy is useful for sleep deprivation where sleep is reduced for several hours on understanding sleep patterns as it is non-invasive and relatively easy to collect data over significant periods of time (commonly two A small number of studies have examined the effect of partial sleep The second method is Polysomnography (PSG) which is a sleep deprivation on athletic performance. Reilly and Deykin (1983) study in which body functions such as EEG, eye movements, reported decrements in a range of psychomotor functions after muscle activity and cardiac activity are measured. PSG provides only one night of restricted sleep; however, gross motor function information on sleep staging and is considered the “gold standard” such as muscle strength, lung power and endurance running for assessing sleep quality and quantity. PSG can be expensive were unaffected. Reilly and Hales (1988) reported similar effects and is labour intensive and is often used primarily for assessing in females following partial sleep deprivation, with gross motor functions being less affected by sleep loss than tasks requiring fast reaction times. PERFORMANCE EFFECTS OF SLEEP DEPRIVATION AND SLEEP EXTENSION The effect of 2.5 h of sleep per night over 4 nights was measured in eight swimmers (Sinnerton & Reilly, 1992). No effect of sleep loss was observed when investigating back and grip strength, lung function There are a limited number of studies which have examined the or swimming performance. However, mood state was significantly effects of sleep deprivation on athletic performance. From the altered with increases in depression, tension, confusion, fatigue and available data it appears that several phenomena exist. First, the sleep deprivation must be greater than 30 h (one complete night of no sleep and remaining awake into the afternoon) to have an Reilly and Percy (1994) found a significant effect of sleep loss on impact on anaerobic performance (Skein et al., 2011). Second, maximal bench press, leg press and dead lifts, but not maximal aerobic performance may be decreased after only 24 h (Oliver et bicep curl. Sub-maximal performance however, was significantly al., 2009) and third, sustained or repeated bouts of exercise are affected on all four tasks and to a greater degree than maximal affected to a greater degree than one-off maximal efforts (Blumert efforts. The greatest impairments were found later in the protocol, et al., 2007; Reil y & Edwards, 2007). For example, peak power has suggesting an accumulative effect of fatigue from sleep loss been shown to be unchanged after 24 h of wake; however, they were impaired after 36 h without sleep (Souissi et al., 2003). Isokinetic From the available research it appears that sub-maximal prolonged performance has also been shown to decrease significantly tasks may be more affected than maximal efforts, particularly after following 30 h of sleep deprivation (Bulbulian et al., 1996). Skein the first two nights of partial sleep deprivation (Reilly & Percy, 1994).
et al. (2011) reported significant decreases in mean and total sprint time following 30 h of sleep deprivation in 10 male team sport athletes. Blumert and colleagues (2007) examined the effects of 24 Another means of examining the effect of sleep on performance is h of sleep deprivation in nine U.S. college-level weightlifters in a to extend the amount of sleep an athlete receives and determine the randomised counter-balanced design. There were no differences in effects on subsequent performance. Mah et al. (2011) instructed any of the performance tasks (snatch, clean and jerk, front squat Sports Science Exchange (2013) Vol. 26, No. 113, 1-4 six basketball players to obtain as much extra sleep as possible the morning and 32% reported waking up at night. Factors such as following two weeks of normal sleep habits. Faster sprint times thoughts about competition (77%), nervousness about competition and increased free-throw accuracy were observed at the end of the (60%), unusual surroundings (29%) and noise in the room (17%) sleep extension period. Mood was also significantly improved, with were identified as reasons for poor sleep (Erlacher et al., 2011).
increased vigour and decreased fatigue (Mah et al., 2011). The same research group also increased the sleep time of swimmers to 10 h Therefore it appears that sleep disturbances in athletes can occur per night for six to seven weeks and reported that 15 meter sprint, at two time points: 1) prior to important competitions and 2) during reaction time, turn time and mood all improved. The data from this normal training. This sleep disruption during normal training may be small number of studies suggests that increasing the amount of due to a poor routine as a consequence of early training sessions, sleep an athlete receives may significantly enhance performance.
poor sleep habits (i.e., watching television in bed), nocturnal waking to use the bathroom, caffeine use and excessive thinking/worrying/ planning. While not documented in the literature, anecdotal evidence Athletes suffering from some degree of sleep loss may benefit from also suggests that athletes such as footbal ers who compete at night a brief nap, particularly if a training session is to be completed in also have significant difficulties falling asleep post competition. the afternoon or evening. Waterhouse et al. (2007) are one of the only groups to investigate the effects of a lunchtime nap on sprint performance following partial sleep deprivation (4 h of sleep). Athletes should focus on utilising good sleep hygiene to maximise Following a 30-minute nap, 20 m sprint performance was increased sleep. Strategies for good sleep include: (compared to no nap), alertness was increased and sleepiness was decreased. In terms of cognitive performance, sleep supplementation The bedroom should be cool, dark and quiet. Eye masks and in the form of napping has been shown to have a positive influence on earplugs can be useful, especially during travel.
cognitive tasks (Postolache et al., 2005). Naps can markedly reduce sleepiness and can be beneficial when learning skil s, strategy or Create a good sleep routine by going to bed at the same time tactics in sleep-deprived individuals (Postolache et al., 2005). Napping may be beneficial for athletes who have to routinely wake Avoid watching television in bed, using the computer in bed early for training or competition and for athletes who are experiencing sleep deprivation (Waterhouse et al., 2007).
Avoid caffeine approximately 4-5 h prior to sleep (this may vary among individuals). According to a 2005 Gallup Poll in the USA, the average self-reported sleep duration of healthy individuals is 6.8 h on weekdays and 7.4 Do not go to bed after consuming too much fluid as it may result h on weekends (National Sleep Foundation, 2006). However, the sleep habits of elite athletes have only recently been investigated. Leeder et al (2012) compared the sleep habits of 47 elite athletes Napping can be useful; however, generally naps should be kept from Olympic Sports using actigraphy over a four-day period to that to less than one hour and not too close to bedtime as it may of age and sex-matched non-sporting controls. The athlete group had a total time in bed of 8:36 ± 0:53 hr:min, compared to 8:07 ± 0:20 in the control group. Despite the longer time in bed, the athlete group had a longer sleep latency (time to fall asleep) (18.2 ± 16.5 Sleep is extremely important for numerous biological functions min vs. 5.0 ± 2.5 min), a lower sleep efficiency (estimate of sleep and sleep deprivation can have significant effects on athletic quality) than controls (80.6 ± 6.4 % vs. 88.7 ± 3.6 %), resulting in a performance, especial y sub-maximal, prolonged exercise. From similar time asleep (6:55 ± 0:43 vs. 7:11 ± 0:25 hr:min). The results the available evidence it appears that athletes may be obtaining demonstrated that while athletes had a comparable quantity of sleep less than 8 h of sleep per night and that increasing sleep (sleep to controls, significant differences were observed in the quality of extension) or napping may be useful to increase the total number of sleep between the two groups (Leeder et al., 2012). hours of sleep and thereby enhance performance. While the above data was obtained during a period of normal training without competition, athletes may experience disturbed sleep prior to important competition or games. Erlacher et al. (2011) administered a questionnaire to 632 German athletes to assess possible sleep disturbances prior to competition. Of these athletes, 66% (416) reported that they slept worse than normal at least once prior to an important competition. Of these 416 athletes, 80% reported problems falling asleep, 43% reported waking up early in Sports Science Exchange (2013) Vol. 26, No. 113, 1-4 Souissi, N., B. Sesboue, A. Gauthier, J. Larue, and D. Davenne (2003). Effects of one night’s sleep deprivation on anaerobic performance the following day. Allen, D.G., G.D. Lamb, and H. Westerblad (2008). Skeletal muscle fatigue: cellular Eur. J. Appl. Physiol. 89:359-366.
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