“They sent it to the house and I just loved it,” said Brady, who took delivery of the new bed at his home in Brookline, Mass., in April and signed on with the company in July. His deal with Simmons Bedding Co. ended last year. “There’s a lot of really disruptive things happening in that industry right now.”

Brady joins Seattle Seahawks quarterback Russell Wilson in Molecule’s stable of athlete endorsers, along with gymnast Nastia Liukin, rower Susan Francia and husband-and-wife distance runners Ryan and Sara Hall. Both Brady’s and Wilson’s deals include equity stakes in the company. Molecule also has a partnership with the New York Mets.

Founded last year by 45-year-old serial entrepreneur Albert Oh and backed by One Rock Capital Partners, a New York City private equity fund that also owns a leading foam manufacturer, Molecule is attempting to crack the crowded online mattress business by offering beds for performance-minded consumers. Its main selling point is foam that helps keep the body cool.

“We invested a lot of time, capital and resources into developing this proprietary airflow foam,” said Oh. The company’s mattresses, he said, move twice as much air away from the body as traditional foam, which helps prevent tossing and turning and promotes the deep sleep that, in addition to other benefits, contributes most to recovery. (Daniel Barone, an assistant professor of neurology at Weil Cornell Medical College and a paid consultant to Molecule, said independent research backs up the claims of keeping body temperature cooler than other foams.)

Professional athletes have begun paying increased attention to sleep and recovery. Oh saw an opportunity to marry that trend with the growing bed-in-a-box industry, in which Casper, Tuft & Needle, Purple and Helix Sleep are already battling it out. “We’re a little bit late to the game,” he acknowledged. “We knew we needed to establish credibility with the right ambassadors.”

That’s where Brady comes in. The 18-year NFL veteran has made a side career of health and wellness through his TB12 brand, which sells meal kits, supplements and workout gear. He also has a line of “athlete recovery sleepwear” with Under Armour Inc. “Sleep is something that I have talked about for many years now, how important it is to recovery not just for athletes but for everybody,” Brady said in a phone interview on a Saturday in August, on his way to Gillette Stadium. He said he sleeps eight to nine hours most nights. “That’s the only way for me. I’m 41 and I’m still playing with all these kids, so I’ve got to get as much rest as possible.”

He struggles, though, on nights after games: “I wish I could sleep good after games. That’s not really the case.” He likes the Molecule mattress, he said, because it offers the right support and keeps him cool.

Brady’s foray into wellness is controversial. His personal trainer, Alex Guerrero, has been barred by the Federal Trade Commission from calling himself a doctor and blamed for causing a rift between Brady and his coach and Patriots ownership. Asked why anyone should take his advice on health and mattress choices, Brady laughed. “I get that a lot,” he said. “I agree. I think at the end of the day being comfortable, sleeping, your mattress, is really a personal choice.”