Sleep is an often overlooked, but vital, component of athletics performance. This article is adapted from the October 19, 2017 issue of Athletics Weekly.
By John Brewer
Most of us spend approximately one third of our lives asleep, and it is easy to view this as time that is “wasted”, with little benefit for training or competing. However, sleep is an essential part of an athlete’s training, and is the time when many of the physiological adaptions to the stimulus of training take place.
How we sleep
The human “body clock” is regulated by a series of cycles known as the circadian rhythm, which determines areas such as digestion, hunger, body temperature and heart rate, as well as the time of day when we sleep.
Sleep scientists have found that we have a series of sleep phases each lasting approximately 90 minutes, which initially take us into alternating periods of deeper and lighter sleep, before gradually emerging to a lighter preawakening stage characterized by rapid eye movement, or REM.
How sleep aids recovery
It is during the deeper, non-REM phases, where sleep does most to help to support athletes. One of the first things to occur is the redistribution of blood supply, with over 40 per cent of the blood that normally goes to the brain during waking hours diverted to the muscles.
At the same time, hormones are released that help with the repair and growth of tissues, something that is essential after a long or intensive run or race. One of the main hormones that is released is human growth hormone, which plays an essential part in rebuilding and developing the proteins that constitute the muscle fibers that will have been repeatedly exposed to the rigors and stimulus of running. Muscle and liver glycogen stores will also be replenished, ensuring that energy reserves are at full capacity in time for the next run.
There is also evidence to suggest that sleep helps to support the body’s immune system. Setting your alarm clock at the same time each day is beneficial and infections are to be avoided. While asleep, the body releases proteins called cytokines.
Some of these help to promote sleep, while others are important in the fight against inflammation and infection, and to combat the physical stresses that are caused as a result of training.
Plan to sleep
Scientists and medical practitioners often recommend exercise during the daytime as a means of enhancing sleep quality, since the body responds to the need to recover and repair by increasing sleeping time and quality. However, since sleep involves a reduction in heart rate, core temperature and blood pressure, it is not advisable to finish a training session or run just before going to bed, because the residual effects of an elevated metabolic rate will make it much harder to fall asleep.
Sleep loss hampers performance
While there are clear and unequivocal benefits from sleep for athletes, continuous sleep loss can be a major issue, with the risk of injury, illness and fatigue all increasing.
The amount of sleep that we require varies from one person to another, with 7-8 hours being the norm for most adults, athletes sometimes needing slightly more. So sleep is as much a part of your training and preparation as your weekly sessions, and without the restorative effects of sleep it would be impossible to train effectively and compete.
Nevertheless, few athletes get a sound night’s sleep before a major competition, due to the combined effects of anxiety and the need to wake at an early hour to get to the start line.
While it is easy to panic if you are not sleeping well on the night before a race, I have never yet seen an athlete fall asleep while racing or competing. Keep things in perspective.
FIVE THINGS YOU SHOULD KNOW ABOUT SLEEP
You can eat yourself sleepy
A study in the American Journal of Clinical Nutrition found that eating high-glycemic carb such as jasmine rice or cereal around lunchtime can halve the time it takes to fall asleep because these foods increase the amount of the sleep hormone tryptophan circulating in the blood.
The Sleep Council, a trade association, recommends a “sleep sandwich” of banana (rich in magnesium and potassium, which help relax muscles), Marmite (rich in B vitamins, which assist the release of tryptophan in the brain) and lettuce.
Failing that, try eating two kiwi fruits, which are rich in the relaxing hormone serotonin, an hour before bedtime; this has been found to help people fall asleep 35% faster after four weeks.
You need anything from 7-9 hours sleep a night
At Stanford University’s sleep disorders clinic, Dr Cheri Mah analyzed the sleep/wake patterns of five female athletes over three weeks and asked them to perform a series of athletic tests that included sprinting, tennis serves and other drills.
On average, the women were getting between six to eight hours sleep a night, which, considering their activity levels, was probably too little. When the same subjects were asked to extend their sleeping one hour per night, their performance in the drills improved significantly and they were able to run faster, hit tennis balls more accurately and exhibit greater arm strength.
However, Dr Neil Stanley, a sleep consultant who was formerly the director of sleep research at the University of Surrey, says you will know if you get enough. “Everyone has a different sleep requirement and some get by on six to seven hours, others need nine,” he says. “If you wake up tired every morning, then you probably aren’t getting enough. It’s that simple.”
Skipped sleep hampers performance
Men who slept less than five hours a night for just one week were shown to have lower levels of testosterone than when fully rested. In the University of Chicago study of fit 24-year-old males, it was found that sleep deprivation caused a 10-15% drop in testosterone, a hormone essential for building muscle mass and bone density.
Dr Jonathan Leeder, an exercise physiologist at the English Institute of Sport in Manchester, has researched the effects of sleep loss and says both strength and endurance “can take a knock” as a result.
During deeper sleep, human growth hormone (HGH) produced by the pituitary gland is released into the blood. It is HGH that enables essential recovery processes such as repairing muscles and converting fat to fuel.
Consequently, too little sleep means the body produces less HGH and more of the stress hormone cortisol that Leeder says “definitely won’t help with muscle recovery and building”.
Sleep trackers can stop you sleeping
Got a sleep tracker on your GPS watch? You could do worse than turn it off. Dr Kelly Glazer Baron, an associate professor at Rush University and a researcher on the sleep disorders program in the department of behavioral sciences, has shown that an obsession with sleep data is causing more insomnia than it is curing.
“For some people, sleep tracking became an obsession which interfered with sleep rather than made it better,” Baron says of her paper in the Journal of Clinical Sleep Medicine. Stanley says the data produced by sleep trackers is “meaningless”.
You should set your alarm for the same time each day
If you do just one thing to aid your sleep, make sure you try to get up at the same time every day, Stanley advises. Hitting the snooze button for a weekend lie-in is not the answer.
Sleep researchers at the University of Arizona showed that a one-hour lie-in at weekends was enough to cause “social jet lag”, a phenomenon caused by a discrepancy between your body’s internal clock and your sleep schedule, that she linked to mood swings and fatigue.
Professor John Brewer is head of the school of sport, health and applied science at St Mary’s University in Twickenham and author of Run Smart: Using Science to Improve Performance and Expose Marathon Running’s Greatest Myths.