Sleep. 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. Sleep is crucial for proper brain functioning, enhancing our ability to learn, memorize, and decide. As we’ll explore, it’s also paramount to fitness and bodybuilding, affecting everything from strength to testosterone levels to pain sensitivity. And yet sleep is something you’re probably not getting enough of to optimize your body, inside and out. Let’s explore how a lack of quality slumber affects your fitness goals and how to maximize your sleep recovery.


More than 750 scientific studies demonstrate the positive relationship between sleep and athletic performance. Here’s just a few of the many things known about sleep deprivation:

🥱 Sleep for less than eight hours nightly, and especially fewer than six, and your time to physical exhaustion drops by up to 30 percent 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.

🥱 Injuries increase. One study showed the odds of athletic injury were 1.7 times greater in those who got less than eight hours of sleep versus those who got more than eight hours.

All of the above can, at the very least, wreck a workout, and that’s before we even address strength. What’s more, research pinpoints 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.

importance of sleep


Some studies demonstrating the benefits of sleep focused on peak and sustained strength. One of these limited eight male subjects (aged 18-24) to only three hours of sleep per night for three nights and tested their strength daily. Those subjects suffered significant and progressive losses of strength in the bench press, leg press, and deadlift, especially after the second consecutive night of sleep loss. Another study, with 15 trained men and two nights of sleep deprivation (three hours of sleep nightly), reiterated the conclusions of the previous study. This study also looked at the effect of “power naps” to recover strength lost by sleep deprivation and concluded: “The use of a one-hour power nap that ended three hours before the strength assessment had a positive effect on weightlifting performance, subjective mood, and ratings of tiredness.”


If you think slumber makes you soft and an alpha dog would never go eight hours, consider that a study of young men limited them to five hours of sleep per night for a week and discovered that their testosterone levels had dropped 15%, concluding: “This study found that skipping sleep reduces a young man’s testosterone levels by the same amount as aging 10 to 15 years.” And that was only a week. (Furthermore, both men and women who sleep too little are markedly less fertile due to hormonal deficits.) Testosterone and growth hormone are crucial to bodybuilding success, and both are replenished via 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 you crave more sugary foods (high-glycemic carbohydrates) when sleep-deprived and your body is less efficient at metabolizing calories. If you want an even scarier conclusion, consider the study that monitored two groups of individuals on calorie-restricted diets. Group A slept five and half hours nightly. Group B slept eight hours. 70% of group A’s loss came from muscle compared to 50% from group B. Conclusion: Sleep is crucial to not just appetite control and fat metabolism but muscle preservation.

importance of sleep


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.


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.


If we still haven’t convinced you of the importance of slumber, consider that a study had people look, randomly, at photos of 23 male and female subjects who had slept eight hours per night as well as photos of the same subjects after not getting enough 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.

importance of sleep



Eight is the magic number. Nine is fine after a particularly exhausting day, but more than nine hours can be counterproductive for healthy adults. Crucially, under eight hours constitutes a sleep deficit for almost everyone. (Some people have a gene that allows them to thrive on six hours nightly, but don’t assume you have that gene. It’s very rare.) Strive to make the eight hours continuous so you cycle through all of the sleep stages, each of which is crucial to recuperation. For example, the REM stage is not only when we dream, it’s also the only time our voluntarily muscles go completely slack, which is crucial for their recovery. If your sleep is so fitful you never go into REM, you’ll never receive its benefits.


Go to sleep and wake up at the same time each day. Also, stay on the same workout and meal schedule. Doing so will set your body’s natural timetable. Change your bedtime or dramatically alter meal and workout timing, and it will likely become more difficult to zonk out.


Relax mentally and physically before turning the lights out. Avoid anything stressful. The ideal temperature for inducing slumber is a chilly 65 degrees. Keep that in mind, and dress in less if your bedroom is warmer. Also, in addition to the relaxing power of the water itself, a warm bath before bed drops your body temperature when you get out of the tub, which helps you nod off.


There are several things you should avoid late in the day.

☕️ Caffeine, the world’s most widely used stimulant, is the most obvious. Be aware that it has a half-life of about six hours. This means that if you have a cup of coffee at 6:00 PM with its 100 mg. of caffeine, you’ll still be wired with 50 mg. (as much as a can of Diet Coke) at midnight.

🍺 Alcohol may impede your sleep, and boozy slumber is often light, absent the crucial REM stage.

📱 The blue spectrum of LED light—the sort generated by computer screens, smartphones, and many modern TV’s—mimics daylight, hampering our body’s release of melatonin, thus delaying sleep cycles. Turn LED screens off at least two hours before bedtime and/or use an app that dims your screen’s blue spectrum during pre-sleep hours.

💊 Except for special circumstances when slumber just will not come, avoid sleeping pills like Ambien. The sleep they induce is, in effect, artificial, lacking the recuperative power of uninduced sleep.


To help make up a sleep deficit, nap for 30-60 minutes in the mid-afternoon. This is when your body’s circadian rhythm dips, lowering your energy, so it’s a good time for revisiting the bed. If necessary, wear a sleep mask to block out light.

For more on improving your sleep see: SLEEP HACKS: 10 Ways to Boost Sleep Recovery