Don't sleep on this Prime Day deal: Amazon's No. 1 mattress cover is down to $18

Mattress covers are one of those things you forget about until you really need it. Then, you either thank your lucky stars you've got a good one or curse the fact that you never got around to buying one. A mattress can be ruined by spills or bodily fluids, and you don't want to have to shell out hundreds, even thousands, for a new one. Good news! For Prime Day. Amazon has slashed the price of its bestselling SafeRest Mattress Protectors — and the queen size is just $18 (was $38)! This is one of many wild deals at Amazon's Prime Day Early Access sale. It's a great chance to stock up on everyday needs, big wishes, and to get a head start on holiday shopping, especially with inflation concerns, notes BlackFriday.com's shopping expert, Lisa Davis. So once your bedding needs are met, check out the rest of the Prime Day deals!

SafeRest Mattress Protector (Queen)

$18$38Save $20

It's no wonder some 192,000 five-star reviewers can't stop raving about this mattress protector — and now, it's on sale. Click the on-page coupon for the deepest discount.

$18 at SafeRest

There's so much to love about this mattress protector. For starters, it's 100 percent waterproof, so it keeps spills, urine and sweat away to ensure your mattress stays in good shape. It also is vinyl-free and has a hypoallergenic cotton terry surface with a membrane back coating, so no squeaking when you move around in bed. It even blocks out allergens like dust mites and protects against bacteria growing on your mattress.

The SafeRest Mattress Protector has a fitted sheet design that works on mattresses up to 18 inches deep. Choose between twin, twin XL, full, queen, king and California king sizes for a fit that's just right for your mattress.

This mattress protector has an army of loyal fans — some 192,000, in fact — and the testimonials are incredible. "My wife went into labor a year and a half ago, and that labor went very quickly...so quickly that she ended up giving birth on our bed in the presence of EMTs," a five-star reviewer said. "The next day, once things had calmed down, I went home to clean up before they came home. For those who have witnessed or gone through childbirth, you know what a mess I arrived to.... Let's just say I was fully expecting to be purchasing a new mattress. To my amazement, once I'd bagged our sheets and this mattress pad, our mattress was perfectly fine. I bought another one immediately and will continue to use this brand as long as it exists."

A fellow fan said they decided to get a SafeRest after one of their cats peed on their bed. "It's crinkle-free, no plastic rustling or crinkling sounds when you touch it, which was honestly my biggest concern. Little noises really irritate me, but thankfully this is silent!" they said. "It fit my mattress easily with plenty of depth and is thin enough that my regular mattress pad still fits over it, as well as sheets, without any problem. I'm very happy with this mattress cover."

Don't feel like replacing your mattress over spills or stains? Nab a SafeRest mattress protector while it's still on sale!

The reviews quoted above reflect the most recent versions at the time of publication.

You need to be an Amazon Prime member to take advantage of these deals. Here's how you can sign up for a free trial, which also gives you complimentary shipping.

See all of our Prime Early Access Sale coverage, here. Shop the top early Prime Day deals on Yahoo Life, get the best Prime Day tech advice on Engadget, learn about Prime Day trends on In the Know, and check out Prime Day car deals on Autoblog.