Short Sleep Impairs Performance
Written by Editor   
Sunday, July 10, 2016 12:00 AM

Three days of sleep restriction slows metabolism and impairs performance in elite cyclists, a new study shows.

Elite athletes often don’t get enough good-quality sleep, but little is known about the effect of this on physiology and exercise performance.  To investigate, researchers enrolled 12 healthy 18- to 35-year-old elite male cyclists in a randomized crossover study. The cyclists had their sleep restricted from 8 hours to 4 hours for 3 days.

Outcome measures before and after the intervention demonstrated that after 3 days of sleep restriction, time to exhaustion decreased by 51 seconds, a difference of 14.4% from baseline, at which time they were getting 7.4 hours of reported sleep.  In addition, maximal aerobic power decreased 2.8%. Maximum volume of oxygen did not change with sleep restriction, consistent with the hypothesis that their aerobic capacity would not change with restricted sleep but that they would have a performance decrement, which is what we observed.  Submaximal heart rate also decreased after sleep restriction, as did peak heart rate. Metabolism also took a hit with short sleep; energy expenditure during 20 minutes of submaximal exercise decreased by about 4%. There was also a slowing of response time of 15.5% on the PVT.

These findings suggest that sleep loss results in performance impairments, including decreased peak power and endurance performance, as well as decreased response speed in elite athletes.  “This is a strong study, with consistent findings that complement our research,” said a sleep researcher.  "What we've found in the laboratory working with healthy adults who don't necessarily exercise a lot is that with chronic sleep restriction people overeat and their energy expenditure drops. So even in people who are exercising a lot, you see this, and that is a very important finding because it means the changes might be even bigger in people who are not as fit.”