Sports Performance

Cup of Mojo

Sleep deprivation can affect workout load. Here's how to avoid that.


Sleep (or lack thereof) and caffeine ingestion often go hand in hand. And in a 2012 study published in the International Journal of Sport Nutrition and Exercise Metabolism, researchers showed that preworkout caffeine can prevent poor workout performance due to sleep deprivation. 

In the study, 16 professional rugby players received either caffeine (approximately 400 milligrams) or a placebo one hour before exercise. Based on the subjects’ reported sleeping habits, they were considered either sleep deprived (six hours or less per night) or non-deprived (eight hours or more). The subjects performed four sets each of bench presses, squats and rows at 85 percent of their predetermined one-rep max and were instructed to do as many reps as possible in each set. Testosterone and cortisol were measured from saliva that was sampled before supplementation, preworkout and postworkout. 

As expected, sleep deprivation led to significant decreases in total workout load, but sleep-deprived subjects who took caffeine performed as well as those who were well-rested. Non-deprived individuals who received caffeine performed better than all other groups. In these individuals, caffeine ingestion boosted testosterone levels both preworkout and postworkout. However, caffeine ingestion was associated with an increase in levels of cortisol (a catabolic hormone) that was greatest in sleep-deprived subjects. 

This was a well-executed study on a relevant population. It should be noted that only 50 percent of the group responded to caffeine supplementation; the others were deemed caffeine insensitive. Most intriguing were the hormonal data illustrating that caffeine boosts T levels. Although the finding of increased cortisol with caffeine is disheartening (but not surprising), there’s light at the end of the tunnel: By digging a little deeper into the study (and doing a little math), it’s apparent that the findings are in favor of a net anabolic effect of caffeine supplementation. Just remember that this heightened effect is only significant if you get a good night’s sleep.

Action Point:To reap the anabolic and energizing benefits of preworkout caffeine, get eight hours of sleep per night and take 200 to 400 milligrams of caffeine 30 minutes before training.