Sleep anchors our circadian rhythms. Everything revolves around it. Our circadian circuitry makes us naturally sleepy at night, keeps us sleeping until we’ve gotten enough, and makes us wake up in the morning and feel wakeful throughout the day. Good thing, too, because we need sleep to live. Sleep deprivation compromises the function of every physiological system of the body. It messes up the nervous system, reducing cognitive function and fine motor coordination. It suppresses immune function, making us more susceptible to illness. And it distorts metabolic function, slowing recovery from recent exercise and promoting weight gain.
“Without adequate sleep, the biological machinery responsible for energy conversion doesn’t function as well,” says Portman. “For an athlete, that has huge implications because our performance is determined by our ability to efficiently convert carbohydrate into energy.”
Many triathletes with full-time jobs cut back on sleep during the week to create time for training. There are those who say this is a counter productive tradeoff, and they cite studies demonstrating the performance-wrecking effects of sleep deprivation in endurance athletes. However, these studies don’t match what triathletes typically do in the real world: get by on less sleep during the workweek, catch up on weekends and sustain this routine long enough to adapt to it. It’s hard to imagine that someone like 2010 Ironman Canada winner Meredith Kessler, who keeps up this common routine, would race better if she slept five hours more and trained five hours less over the course of the week.
However, while Kessler’s routine might be optimal for athletes in certain situations, it’s not perfect. In a perfect day, you would get all the sleep you needed, which is 7.5 to eight hours for the average person, more for athletes in heavy training (which increases sleep needs), and ranges from as little as five hours to as much as 10 for individuals who are wired a little differently. And in a perfect world, you would be able to get as much sleep as you need every night without making any sacrifices in your training volume. You would be able to do what full-time triathletes such as TJ Tollakson do: sleep eight hours at night, nap two hours in the afternoon and train 30 hours a week.
In the reality you live in, you need to find the best balance you can. Avoid cutting back on sleep to train more if possible, but if you just can’t find enough time in the day to do the training you need, then reduce your sleep moderately on work nights and catch up when you can. Don’t go overboard and pay attention to your performance and how you feel. If you start to feel lousy and your performance stagnates, you’re probably trying to train too much on too little sleep and need to shift the balance back.