Mattress shoppers are buying online more and more

Brick-and-mortar mattress stores aren't resting so easy.

That's because online retailers are laying claim to what may have seemed like sacred territory for their physical competitors.

The plush surfaces where many humans spend a third of their lives may have seemed immune to e-commerce just one decade ago. But not so anymore, given a boom in online mattress start-ups, detailed online user reviews, free shipping and no-hassle returns.

Physical retailers were told a cautionary tale this week when Reuters reported that Mattress Firm, the country's largest mattress retailer, is considering filing for bankruptcy.

The company is saddled by expensive store leases and might be pressed to shutter some of its 3,000 locations, sources familiar with the situation told Reuters.

As of Monday, the company hadn't made any final decisions, and did not return a request for comment.

Mattress Firm has been on shaky ground after losing Tempur Sealy International, the maker of Tempur-Pedic mattresses, as a supplier last year.

It also has been dogged by financial troubles of its parent company, Steinhoff International Holdings, in the wake of an accounting scandal.

But analysts agree that for Mattress Firm and other brick-and-mortar retailers, there are broader complications at play.

Their most serious competitors are online retailers who have found quick success with bed-in-a-box models - often mattresses that come compressed and vacuum-sealed to your door and then expand to their full sizes once unwrapped.

No need to come to a store, no need to lay down and feel for yourself.

Just like everything else.

'If you told (shoppers) 10 years ago, ‘You're going to buy a bed-in-a-box and you're going to love that,' they'd say ‘What?,'” said Brian Yarbrough, a consumer research analyst at Edward Jones.

He compared the shift to early skepticism that Amazon.com couldn't break into selling apparel 'because people want to touch and feel it.” (Amazon chief executive Jeff Bezos owns The Washington Post.)

Online mattress start-ups - including Nectar, Tuft and Needle, and Leesa - have won customers over with offers to buy mattresses online and try them out for a few months.

Companies will offer full refunds for returned mattresses and, in many cases, donate used mattresses to charity.

Casper, for example, raked in over $100 million in sales in 2015, its first full year.

The mattresses are sold at Target stores, and earlier this year it opened its first permanent location in New York. The store was outfitted to feel like a bedroom where customers are encouraged to relax and even snooze.

More than a dozen other pop-ups have opened nationwide in the past few years.