Even if it doesn’t necessarily feel that way. Sleep doesn’t just make us less tired; it helps our bodies recover and makes them healthier. Our expert, Dr Daniel A. Bizjak from Ulm University Hospital, has clearly ranked sleep as number one when it comes to recovery boosters: Sleep quality and duration have by far the strongest evidence base of all the recovery measures analysed. Here, we’ll take a closer look at exactly what happens during sleep and why a lack of sleep effectively sabotages your training.
Sleep is not a uniform period of rest, but a structured cycle comprising deep sleep and REM phases (REM stands for Rapid Eye Movement) – and both serve a specific purpose for athletes.
During deep sleep, the body releases growth hormones. These promote the repair of muscle tissue and protein synthesis, thereby contributing to the benefits of training. Anyone who does not get enough deep sleep produces fewer growth hormones – and thus hinders the very process they have worked so hard to achieve through training. At the same time, deep sleep appears to involve a sort of cleansing mechanism in the brain that flushes out metabolic waste products that have accumulated whilst awake.
Scientific studies suggest that motor skills tend to be consolidated during REM sleep. This applies generally, but is likely also true for sport: whatever you have learnt on the bike or in the gym – pedalling technique, body tension, coordination – could therefore be consolidated during this phase.
How much sleep do cyclists need?
The general recommendation of seven to nine hours also applies to active people. Keen amateur cyclists should aim for the upper end of this range. A widely cited study involving basketball players at Stanford University in California showed that those young men who extended their sleep duration to ten hours saw measurable improvements in their reaction times, sprint performance and shooting accuracy.
This is particularly relevant for endurance sports: roughly speaking, a lack of sleep impairs endurance performance and makes it feel more strenuous. It also affects the hormonal processes that are important for endurance. This means that, for the same level of exertion, the body works less efficiently – and recovers more slowly afterwards. You may be able to see this quite clearly with a heart rate monitor. When recovery is poor, your heart rate is often elevated much sooner than it would be after sufficient rest.
What many people underestimate is that chronic, mild sleep deprivation is more problematic than a single bad night’s sleep. Van Dongen and colleagues from Pennsylvania demonstrated as early as 2003 that six hours’ sleep or less per night over a two-week period leads to cognitive impairment equivalent to that seen after 24 to 48 hours of complete sleep deprivation – even though those affected subjectively felt hardly any impairment. This is an important point: those who consistently get too little sleep often no longer notice it.
Another important aspect: there is often debate about the role of sleep duration versus sleep quality in terms of recovery. This is a lively debate, as our expert Daniel A. Bizjak points out – as well as referring to a specialist article in *Children* magazine. Its conclusion: both sleep duration and sleep quality are crucial, although recent studies often rate quality as more significant for health; future research, however, should not view the optimal sleep duration as an absolute value, but rather in terms of how close it is to an individual’s biological optimum.
Not getting enough sleep can throw hormone levels out of balance. Cortisol, the stress hormone, can rise. Testosterone, on the other hand, tends to fall. Put simply, the body then breaks down resources rather than building them up. Muscle protein synthesis – that is, the use of protein for repairing and building muscle – is inhibited.
Added to this is the risk of injury. A large longitudinal study of adolescents showed that sleeping for less than eight hours was associated with an increased risk of sports-related injuries. Similar links have also been described in adults. Put simply: anyone who trains whilst overtired is likely to make more mistakes, react more slowly and may be less able to protect themselves from overuse injuries. The immune system also suffers from a lack of sleep.
And then: we’ve all been there – after a bad night’s sleep, even the thought of a long ride feels like a struggle. Imagine, on top of that, getting a puncture right at the start...
What really helps: sleep hygiene for cyclists
The good news is that, unlike some other ways of recharging your batteries, a good night’s sleep costs nothing. However, it isn’t something you can simply buy, and it certainly cannot be replaced by technology. There are, however, a few factors that make a measurable difference.
Regularity is important. If you go to bed and get up at the same time every day – even at the weekend – you stabilise your body’s rhythm and may also improve the quality of your sleep.
Evening exercise and sleep don’t really go hand in hand. Intense late-evening sessions in particular raise your body temperature and cortisol levels, both of which make it harder to fall asleep. If you have no other choice, you should allow at least 90 minutes after your workout before going to bed.
Power naps can help to reduce sleep debt (meaning the difference between sleep requirements and the actual amount of restorative sleep) in the short term – but only if they are short and do not take place too late in the afternoon. 10 to 20 minutes are enough; sleeping for longer leads to deep sleep and leaves you feeling groggy rather than refreshed upon waking.
Light and Temperature are often underestimated factors. The bedroom should be cool (around 18 degrees), dark and, as far as possible, free from electronic devices with screens.
- Regular bedtimes: help to stabilise the sleep-wake cycle
- A cool, dark bedroom: promotes melatonin production and sleep
- No intense exercise after 8 pm: helpful for those with trouble falling asleep, with varying effectiveness depending on the individual
- Power nap (10–20 mins): effective in the short term when you’re sleep-deprived; timing is crucial
- A screen-free period before bed: sensible and easy to put into practice
- Sleep tracking via wearables: provides guidance, but has no diagnostic value as it is prone to error – do not read too much into it!
Tim Farin
Editor