"It's well known that if you sleep more, you recover better," said Under Armour senior vice president for global apparel product Glenn Silbert, arguing that the 21 hours of the day even a serious athlete spends not working out is as important for fitness as the workout. "We've gotten deeper into the 24-hour life of the athlete.''

Under Armour has partnered with Johns Hopkins Medicine to figure out the best ways to record athletes' sleep data and recommend ways to get better rest and is working Brady's new sleepwear into the company's ongoing suite of web-connected fitness products, like UA Record , which lets users upload their heart rate and other health data via their smartphones, and UA HealthBox , a $400 product suite that includes a fitness band, scale and heart-rate monitor.

Brady's "super pajamas" are not a gimmick. There's a growing emphasis in medicine on the value of sleep to performance, in sports and elsewhere. The high-profile product also bolsters Under Armour's push to get itself involved in the convergence of digital technology and use of physical data to help customers manage their wellness.

If Spike Lee's Mars Blackmon doppelganger thought Michael Jordan's greatness "gotta be the shoes," Under Armour is betting that Tom Brady's drive for a record-setting fifth Super Bowl win this Sunday is all about the jammies. As in, the $170 pajamas the Baltimore athletic-wear company began selling with Brady's endorsement last month.

The web-connected fitness business is the fastest-growing unit at Under Armour, and it is a company in need of new, exciting business lines to keep Wall Street and investors happy. Its stock fell 23 percent this week after announcing fourth-quarter earnings that fell well short of forecasts, and shares are down near-75 percent in the past year. The web-connected business line is still less than 2 percent of Under Armour revenue.



The science behind the pajamas is as straightforward as one of those quick slant passes Brady has made a living on for years.



The fabric is infused with bioceramics, a technology that scientists believe helps the body better manage far infrared rays, which can help regenerate tissue and reduce recovery time from training while an athlete sleeps. Part of the idea is that the technology helps reduce inflammation and promote better blood circulation, according to Under Armour.



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Under Armour and Brady worked together for more than a year to figure out how to get the bioceramics into the fabric so it was still comfortable. The quarterback, who was not available for an interview ahead of the Super Bowl, had used bioceramics in a gel form before talks with the company about the sleepwear began.



"We push our bodies so hard, and our bodies need time to rejuvenate," Brady told Sports Illustrated. "It is something I have been doing for a long time and is really important."

The pajamas don't look obviously different than other Under Armour gear. The top fits fairly snugly, and the short pajama bottoms (Brady says he wears long pants) are designed to fit loosely. If a customer wore them to the gym, they wouldn't stand out, except for the "Rest Win Repeat" slogan on the back of the shirt.

The key to the enterprise — and, indirectly, the partnership with Johns Hopkins Medicine — is less about bioceramics than it is about digital health care, and adding utility to the company's UA Record and UA HealthBox products, built around acquisitions the company made earlier in this decade, Silbert said.



— By Tim Mullaney, special to CNBC.com