According to Sleep Advisor, market trends heavily point toward May being the best month to purchase a new mattress. This is true for several reasons. There are new mattresses usually coming out for perusal in June that consumers buy up through September. Toward May, stores that sell mattresses will want to start getting rid of the inventory that's piling up over time. They'll then start slashing prices, and you can reap the benefits. That means you can usually get a good deal.

There's always the suggestion of buying during holidays where several sales are going on. For instance, Memorial Day weekend is a great idea that brings the "May factor" into focus since stores are clearing inventory as well as the sales that tend to happen around Memorial Day. Most holidays, including Black Friday and Thanksgiving, Labor Day, and President's Day, are also great options to start looking for a mattress.

If you don't want to wait until the holidays, you can also check overstock sales as well as online stores that heavily discount home goods like mattresses and the like or physical stores that are closing. This is a surefire way to get in on some of the best deals you possibly can, especially if you don't mind if you're getting an older model — in some cases, a mattress is a mattress, after all. In the end, you need something to replace what you were sleeping on, and that's all. 

These buying times and places should help you figure out when the best time to buy a mattress is for you personally as well as for the general populace. But generally speaking, if you need a mattress right now, you'll have to bite the bullet and go ahead and buy now — sometimes things can't wait for the perfect time.