Sleep is becoming the elite athlete's secret weapon, and the NFL is just starting to discover how to harness its potential.
Gary McCoy, a sports science consultant for many NFL teams over the last few years, watched a pair of receivers sweat their way through a training camp session in 2015. One receiver was a celebrated veteran, the other a speedy young up-and-comer. Both wore high-tech sensors that monitored their heart rates, body temperatures and physical stresses during the intense practice. The sensors confirmed that the stress data for each receiver was roughly equal: Practice was just as hard for both of them.