Dr Sarah Gilchrist explains why sleep is so important for exercise and how to be sleep strategic
Do you wake up feeling lethargic, tired and grumpy? If so, you might not be getting enough sleep – more specifically, deep sleep.
This can be a real stumbling block if you’re looking to perform on the bike, because getting a good night’s sleep is essential to your body’s physical repair process.
We spoke to Dr Sarah Gilchrist to find out how to sleep soundly and feel stronger, brighter and faster.
Deep sleep: where the magic happens
Dr Sarah Gilchrist has a doctorate in sleep and athletic performance, and formerly worked with GB rowers at the Beijing and Rio Olympics. She’s now helping recreational athletes. In short, Gilchrist is an authority on advising sportspeople on how to regenerate and come back stronger.
“All of us have a 90-minute sleep cycle that covers four stages,” she says. “The first couple of stages are light sleep, so if you were to nap for 20 to 30 minutes, that’s what you’d fall into. Your fourth stage is the rapid eye movement [REM] stage, where you tend to dream and is related to emotional control. So, our mental health, positive consolidation of emotions and coping strategies.
“It’s the third stage where you enter deep sleep, which is often called ‘slow wave sleep’ and occurs about 60 minutes in. This is where recuperation and restoration happens. At a physiological level, this is the time when growth hormone is released, glucose metabolism is regulated and protein synthesis cranks up. Both are essential to build muscle.
“It’s also the time for memory consolidation, a place where you take things on cognitively. That means skill acquisition, like handling your bike better.”
According to a 2021 sleep consensus statement in the British Journal of Sports Medicine, “the duration and composition of normal sleep changes across the life cycle. At the ages relevant to aspiring and established athletes, a sleep of eight to 10 hours for an adolescent (aged 15 years) contains approximately 57% light sleep, 22% deep sleep and 21% REM sleep; and a sleep of seven to nine hours for a young adult (aged 30 years) contains around 61% light sleep, 16% deep sleep and 23% REM sleep”.
This slight age-related reduction in deep sleep is down to the significant growth seen in the teenage years.
The impact of poor sleep
That same paper, although aimed at elite athletes, highlighted how 50 to 78 per cent of athletes experience sleep disturbance, while 22 to 26 per cent suffer highly disturbed sleep.
That significantly impairs both the deep and REM sleep stages, which has repercussions for both cycling performance and general health.
“There are many studies that show the determinantal impact of ‘sleep restriction’ on an athlete,” says Gilchrist. “One study took a group of athletes, put them to bed, woke them up at nightly three-hour intervals and sent them back to sleep again. They showed that an athlete’s physical prowess and psychomotor skills were reduced.”
“You see a fall in stamina at submaximal levels,” adds Gilchrist. “It’s the same on the anaerobic side, where maximal power output drops, and the same’s been seen with a tennis serve. Speed drops through consistent lack of sleep, which is down to a drop in isometric force.
“Slower reaction time and poor decision making, plus a greater chance of injury and illness… It’s all bad. We also know that chronic lack of sleep leads to certain diseases later in life.”
Know your chronotype
How do you know if you’re lacking deep sleep? Apart from that foggy grumpiness, because it’s clearly a key part of the 90-minute cycle, anyone who sleeps for less than the recommended number of hours is likely to record insufficient deep sleep.
So, what can be done? Well, playing to your performance and sleep strengths will help. Your chronotype is the natural inclination of your body to sleep at a certain time, or what’s more commonly known as being a lark or an owl.
“Again, there have been studies into this. One study found about 50 per cent of elite athletes were morning types, around 9 per cent were evening types and the rest sat somewhere in between. For the general population, you see various numbers bandied about, but it tends to be a third of people morning, a third in the evening and a third in between.”
You’ll know if you’re a morning type because you may be almost irritatingly chatty over morning coffee. The reverse is often true of evening types.
In a perfect world, training to match your chronotype will maximise gains and help you sleep better later on. That’s the ideal. Which arguably isn’t realistic. What happens, for instance, if you’re a morning type who has no other option but to squeeze in an evening gym session? How can you boost your chances of a good night’s sleep?
Be sleep strategic
“When you exercise, typically your adrenaline levels rise, cortisol increases, your heart rate goes up, as does your core temperature. None of that is conducive to sleep,” says Gilchrist. “But you can be strategic to improve your chances of sleeping well.
“I’d advise eating your main meal earlier in the day and a snack after your session, as too much food cuts your chances of falling asleep. Hydrate but don’t drink too much as you’ll spend all night visiting the loo.
“Shower, stretch and have some downtime before hitting the sack, as it’s beneficial to lose a little quantity if quality’s higher. The next day, you should return to your normal sleep routine.”
That downtime is key, says Gilchrist, who adds that watching TV is fine as long as you ensure your choice of programming isn’t too stimulating. It’s the same with scrolling on your smartphone, which taps into a recent development in the world of sleep – that while bedtime smartphone use isn’t advised, it’s not because of the blue light.
“Professor Michael Gradisar’s doing a lot of research on this and observed that the blue light emanating from our phones isn’t strong enough to suppress melatonin, which is the hormone that tells you to sleep,” says Gilchrist.
“The problem is actually more the ‘scroll hole’ you might fall into when looking at platforms like Instagram or YouTube. It’s arousing and can inhibit sleep.”
Further raising your chances of proficient sleep, and deep sleep, are the use of eye masks, banishing caffeine after lunchtime, changing the tog of your duvet to match the season and consuming tryptophan-heavy foods.
“Tryptophan is a precursor to melatonin and is found in milk, almonds, many plant-based foods and turkey,” says Gilchrist. “We used to get through so much turkey mince with the rowers to help them sleep.”
You can also try afternoon napping, although Gilchrist recommends no more than 30 to 90 minutes to fit in with the sleep cycle. Out of this range, you’ll awake groggy and your deep sleep could be impacted later on. You should also look to sleep bank if a period of anticipated sleep loss awaits, such as when travelling abroad for your goal sportive.
One study in collegiate basketball players showed that sleep extension, comprising a 10-hour time in bed each night for five to seven weeks, improved reaction time, sprint times, mood and free-throw shooting accuracy.
Further research is required to see whether the purported benefits of sleep extension can be realised with shorter additional nightly sleep and over a more realistic shorter timeframe.
So, there you have it. Pay as much attention to what you do off the bike as on it and you’ll soon be deep-sleeping your way into the yellow jersey. Sleep easy, feel strong.