Sleeping for success

If you’ve ever suffered a chronic sleep shortage, you probably won’t be surprised to hear that sleep deprivation can impact on your physical performance. Over the years, numerous studies have established that a chronic sleep shortage (ie cumulative sleep loss – not just the odd night’s poor sleep) can adversely affect sprinting ability, increase the risk of injury and lead to disturbances in metabolism, which further impacts on physical performance. However, what is less well understood is how sleep loss impacts recovery from exercise. Although this is a little-researched topic, one recent study by scientists in South Africa suggests that sleep deprivation could be harmful for recovery from prior exercise [Eur J Appl Physiol. 2017 Apr;117(4):699-712]. It also suggests that this sleep loss doesn’t need to be chronic; even one night’s poor sleep could dent your performance the following day.

The research

In this study, researchers set out to compare the recovery of cyclists following a single bout of high-intensity interval training. Sixteen well trained male cyclists took part in the study. All of the cyclists firstly underwent physiological and psychological testing. These tests included measures of peak power output, blood pressure, measures of sleepiness and motivation to train. Following testing, all of the cyclists undertook a bout of intense interval training, which took place at 6pm that evening. Following this training session the cyclists were then divided into two groups; one group was allowed to enjoy a normal night of sleep, where the average sleep length was just under eight hours. However, the other group was only allowed to take half this amount of sleep – ie under four hours. The next day, the pre-training tests were repeated at 12 and 24 hours to see whether there were any differences between the two groups. After a further period of two weeks, the whole procedure was repeated but the groups reversed – ie the cyclists who had adequate sleep in the first trial were now only allowed reduced sleep and vice versa (a so-called ‘crossover’ study). The results were then analysed.

The findings

The first key finding was that when the cyclists went short of sleep, they suffered a significant drop in their peak power output when compared to the cyclists who were allowed a full night’s sleep. With sleep deprivation, peak power outputs dropped by around 0.22 watts per kilo of bodyweight – around 18 watts for an 80kg cyclist. That compared to around a loss of just 0.05 watts per kilo when sleep was adequate (around 4 watts for an 80kg cyclist). The increased loss in peak power output following sleep loss signifies significantly impaired recovery. In addition, the cyclists’ systolic blood pressure remained raised even at 24 hours following the interval training session when sleep-deprived, whereas it fell (a sign of recovery) when they had a full night’s sleep. Unsurprisingly perhaps, the cyclists also reported feeling worse subjectively following insufficient sleep, feeling sleepier and much less motivated to train (another sign of incomplete recovery).

Peak Performance verdict

This study is noteworthy because unlike other studies on exercise performance, this one focuses on recovery and suggests that even one night’s poor sleep could impair the ability of the body to recover following intense training – a finding that has real implications for athletes participating in multi-day events such as adventure races or long-distance cycling events. What are the mechanisms behind this poorer recovery? The researchers were at a loss to explain why, which suggests this is an area where more research is needed. In the meantime however, it seems that when maximising your recovery is the priority, getting a full night’s sleep following intense training should be part of an athlete’s recovery strategy.

Practical suggestions

Here are some tips to help you maximise your sleep duration and quality when recovery is a priority:

  • Stick to regular bedtimes. If you regularly have to get up early, ensure your bedtime is early enough to allow you to wake feeling reasonably refreshed.
  • Take the time to wind down before bedtime. Don’t get involved in any kind of anxiety provoking activities or thoughts in the 90 minutes before bedtime.
  • Avoid using a computer or viewing any device with a bright screen before retiring – eg mobile phone or laptop surfing.
  • Minimise or avoid caffeine intake after 4pm.
  • Make sure your bed is comfortable; experiment with mattresses and pillows to increase sleeping comfort.
  • Keep your bedroom quiet, well ventilated and not too warm.
  • Sleep alone if the activity of your partner (eg snoring, turning over, sleep talking) disturbs you.

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