Better sleep. That's all that could be standing between you and a new PB.
Too good to be true? Not according to Mara Yamauchi, who set a new marathon PB (2:25:03) at the International Women's Marathon in Tokyo in November. "Sleep is one of the most important elements of my routine, because it is crucial for recovery, when the body adapts to the stimulus of training and repairs itself."
Eight or more hours' sleep a night and two-hour afternoon naps aren't realistic for most recreational runners. But whether you run a 2:30 or a 4:30 marathon, you too should up your sleeping game, says Professor Jim Horne from the Sleep Research Centre at Loughborough University. "Consistent, regular, good-quality sleep is vital when training for any endurance event," says Horne. "Besides just feeling more rested and ready to tackle the day ahead, adequate sleep – at least seven hours, uninterrupted – can make a big difference in your recovery."
Sleep is divided into five stages – the first four are characterised by non-rapid eye movement, while stage five is marked by rapid-eye movement (REM). Depending on age and how rested the individual is, REM and non-REM patterns cycle throughout the night about every 90 minutes. When brain waves are measured in sleeping subjects they show a slow wave during stages three and four.
"When it comes to fitness, slow-wave sleep is the most important of the night, as this is when human growth hormone (HGH) is released by the pituitary gland at the base of the brain," says Horne. "It's necessary to build and repair muscles and bones, and it causes us to use more fat for fuel." Loughborough University studies revealed that when sleep is restricted over several nights, HGH release is markedly reduced. "Without the right amount of HGH in the blood, recovery from workouts is hindered, prolonging the time it takes the body to build a strong aerobic engine," says Horne. As a result, the sleep-deprived athlete responds poorly to training both in the short term and over the course of a season.
As HGH decreases, another hormone, cortisol (the 'stress hormone'), increases. "Too much cortisol can prohibit the body from recovering fully and interfere with the repair and growth of soft tissue," says Horne.
A recent study published in The Lancet medical journal showed that a period of decreased sleep over only a few days can cause a disruption in glucose metabolism – the process responsible for storing energy from the food we eat, and why marathon runners carbo-load before a big race or long run.
"With impaired glycogen synthesis, runners can't get their glycogen stores as high, which means they may hit the wall sooner during longer runs or races than if they were well-rested," says Horne.
Other studies have revealed that people suffering from sleep deprivation often make poor decisions, can't focus and become unmotivated. Lack of sleep can also compromise your immune system, which is already vulnerable during training: those who get six hours or fewer of sleep have 50 per cent less immunity protection than those who get eight hours per night.
While most people need seven to nine hours of sleep a night to feel fully rested, the number of hours varies by the individual.
To find your magic number, try this: "Go to bed at the same time every night and wake up naturally," says Mark Blagrove, sleep psychologist from the University of Wales. "By the fourth day, you'll have paid off your sleep debt, and should wake up refreshed." Take note of how many hours you slept – that's your goal, he says.
While you may feel the need to sleep a little longer when training for a half-marathon or marathon, the key to full recovery is not just how many hours of sleep you get, but the quality of your sleep. "For the highly trained athlete, sleep becomes more important, but the hours might be less because their sleep is more effective," says Paul Martin, author of Counting Sheep (Flamingo; £7.99).