We spend one-third of our lives doing it—or at least we should. Sleep bolsters our immune system, and a deficit of it has been linked to such catastrophic health consequences as cancer, Alzheimer’s disease, and heart failure. It’s crucial for proper brain functioning, enhancing our ability to learn, memorize, and decide. As we’ll explore, it’s also of paramount importance to bodybuilding, affecting everything from strength and testosterone to pain sensitivity. Yet sleep is something you’re probably not getting enough of to optimize your body, inside and out.
More than 750 scientific studies demonstrate the positive relationship between sleep and athletic performance. Here are just some of the many things known. Sleep for fewer than eight hours nightly, especially fewer than six, and your time to physical exhaustion drops by up to 30% with a similar reduction in aerobic output. Your metabolic, respiratory, and cardiovascular capabilities are hampered. Lactic acid builds up faster. The ability to cool yourself via sweating is impaired. Motor skills are reduced. One study showed the odds of athletic injury were nearly doubled by a two-hour sleep deficit. All of the above can wreck a workout, and that’s before we even address strength. What’s more, research points to the final two hours of an eight-hour sleep—a phase when the brain is putting it all together, completing the physical and mental tune-up, so to speak—as critical to athletic performance.
Some studies demonstrating the benefits of sleep focused on peak and sustained strength. One of these limited eight male subjects (ages 18 to 24) to three hours of sleep per night for three nights. Those subjects suffered significant and progressive losses of strength in the bench press, leg press, and deadlift.
If you think slumber makes you soft and an alpha dog would never go eight, consider that a study of men in their 20s—limited to five hours of sleep per night for a week—discovered that their testosterone levels had dropped so dramatically that they had effectively “aged” by 10 to 15 years. (Furthermore, both men and women who sleep too little are markedly less fertile because of hormonal deficits.) We don’t need to tell you how crucial testosterone and growth hormone are to bodybuilding success, and both are replenished with eight hours of sleep.
Similarly, many associate sleep with growing fat. After all, you burn more calories when awake than when not. To the contrary, you should associate sleep with getting lean. Multiple studies prove that you crave more sugary foods (high-glycemic carbohydrates) when sleep deprived and that your body is less efficient at metabolizing calories. For an even scarier conclusion, consider the study that monitored two groups of individuals on calorie-restricted diets. Group A slept five and a half hours nightly. Group B slept eight hours. Some 70% of group A’s calorie loss came from muscle compared with 50% from group B. Conclusion: Sleep is crucial to not just appetite control and fat metabolism but also muscle preservation.
A wealth of research demonstrates that a sleep deficit hurts your emotional equilibrium— you grow frustrated and angry faster—and your ability to focus on tasks. These factors can negatively impact workouts where attention and motivation are paramount.
One surprising consequence of even minor sleep deprivation is it makes you more sensitive to pain, which means you’re more likely to end those sets of squats earlier after an incomplete night of sleep than when you get a full eight hours.
If we still haven’t convinced you of the importance of slumber, consider that a study had people look, randomly, at photos of male and female subjects who had slept five hours per night as well as photos of the same subjects after getting eight hours of z’s. The same faces after less sleep were rated less healthy and significantly less attractive than when the subjects got their eight hours. We really do need our beauty sleep.
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