I have something a little bit different to share today. Hopefully today’s post will offer a little motivation for everyone to value sleep.
All over the health and fitness world, there are people rising before the sun to train hard and get a workout in. To train for a marathon, sometimes you need to get that long run in early before work. To hit that squat PR, you’re at the gym at 6am week after week. The fitness world is full of some of the most motivated and determined individuals. Everyone has a goal: to feel better, to PR, to complete a race, to win a competition. It’s no secret that those things require hard work. On top of that, everyone is busy. Oftentimes, the workout occurs at the cost of sleep. But have you ever considered what this trade-off really means?
Sleep deprivation has been shown to have negative effects on athletic performance. Hitting the gym instead of sleeping may be stalling your progress. Researchers tested the effect of partial sleep deprivation on weight lifting and found that lack of sleep was detrimental1. In this study, participants were allowed only 3 hours of sleep for 3 nights in a row (the participants normally slept 8 hours per night) and then tested their maximum lifting capacity for bench press, bicep curl, leg press, and deadlift each subsequent day. Their maximum lifting capacity under sleep deprivation was compared to their maximum lifting capacity in a non-sleep deprived state. General feelings of sleepiness rose each day, but what is more significant and perhaps unexpected was the effect on the lifts. While there was not a significant effect on bicep curls, there was a statistically significant decline after 3 nights of sleep deprivation in maximum weight lifted for the deadlifts, bench presses, and leg presses.
In this figure, each point represents a subsequent day of sleep deprivation, with the first data point taken immediately before the first night of sleep deprivation. The Normal is the control with normal sleep, and PSD refers to partial sleep deprivation.
There was also an increase in general perceived exertion during the final day. Participants also reported increasing feelings of sleepiness and fatigue. Researchers hypothesize that these factors may be responsible for the decreased ability to lift heavy. Consider this: you would be able to push yourself harder in a non-sleep deprived state, and ultimately see greater fitness gains.
If physiological data is more your thing, perhaps the following study out of France will convince you. Highly trained endurance athletes were first tested at baseline (normal sleep) and then again several days later after a night of sleep in which they were forced to say awake for 3 hours, thus sleep depriving them. After a warm up, the athletes rode stationary bikes for 20 minutes at a predetermined steady exercise intensity, and then maxed out their intensity to exhaustion. After partial sleep deprivation, at submaximal steady intensity, the athletes had significantly higher ventilation and heart rates. Lactate accumulation was also higher. At maximal exercise, the maximal intensity was no different, but the peak oxygen consumption was lower2. Practically, this means that the cyclists were able to reach the same maximum intensity, but it felt much harder and put much more stress on their bodies.
You may be thinking—“how is this relevant? I get more than 3 hours a sleep a night. I’m not sleep deprived.” Unfortunately, consistently under-sleeping (sleeping less than an individual’s daily need) can lead to the accumulation of sleep debt. Sleep debt is essentially the accretion of all those nights that you did not sleep as much as necessary, and leads to increasingly strong feelings of sleepiness and fatigue. Sleep loss is cumulative. For example, if an individual physiologically needs 8 hours of sleep per night and for 7 days sleeps only 7 hours each night, that personal has a sleep debt of 7 hours. To feel well rested, this person would need an additional 7 hours of sleep on top of his or her daily need for 8 hours a night. Many studies have found that when subjects are forced to spend extra time in bed, they will sleep a far greater amount at the beginning of the study than at the end, suggesting that they began with a large sleep debt and then finally made up for it with extra sleep and resumed sleeping a normal amount.
A study done right here at Stanford demonstrated the practical applications of this by looking at the relationship between sleep extension (extra sleep) and the performance of Stanford men’s basketball players. The players tested timed sprints and shooting accuracy at baseline sleep and then after 5-7 weeks of experimental intervention. In this intervention, the players spent a minimum of 10 hours in bed a night. The athletes slept about 110 minutes more per night during the intervention, and improved their 282 foot sprint times by almost a full second. Additionally, they improved their 3 point and free throw accuracies by about 9% each. They also experienced increases in mood and reaction times3. The takeaway? By erasing their sleep debt, the basketball players improved their sports performance!
The ultimate takeaway is that sleep is incredibly important, and plays a major role in athletic performance. It may not be worth sacrificing in favor of an extra workout. Sleep should be a priority, and I urge everyone to make an informed decision and consider this when planning his or her schedule. The benefits of sleep may outweigh the benefits attained from the workout. To figure out how much sleep you actually need, you need to first make up your sleep debt (which most people have), and then sleep sufficiently such that you are not sleepy or drowsy during waking hours.
Do you get enough sleep every night?
(2) Mougin, M. L. Simon-Rigaud, D. Davenne, A. Renaud, A. Garnier, J. P. Kantelip, P. Magnin. Effects of sleep disturbances on subsequent physical performance. European Journal of Applied Physiology and Occupational Physiology, 1991, Volume 63, Number 2, Page 77.