It's hard not to succumb to the mattress sales pitches that seem to promise the moon — less stress, deep sleep, no more lower back pain.

And if you were just starting to wrap your head around the concepts of a Sleep Number bed vs. a Tempur-pedic, along come new buzzwords: Coil count. Cashmere. ComforPedic. Latex. Pillow-top.

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Inner-spring is the most common mattress type. You can pay from $200 to more than $4,000.

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Several companies make memory foam mattresses, which are designed to minimize pressure.

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A mattress is probably the single most difficult product to buy, says Tod Marks, senior editor at Consumer Reports.

The names of mattresses can differ from store to store, so it's hard to compare them. Plus, they're often on sale. "But you really can't see inside that mattress, so you don't know what you're paying for," Marks says. "You're just basically listening to the marketing spiel."

At the same time, it's an important purchase.

"I would say that a good-quality mattress is about as important as diet and exercise, when it comes to feeling good and having a productive day," says Nancy Shark, executive director of the Better Sleep Council, the consumer education arm of the International Sleep Products Association. "You should love your bed."

We all want to sleep well. So let's look at a few things to help us dump that lumpy old mattress for a new dream bed.

Mattress types

There are loads of beds — from futons to waterbeds to Craftmatics. But to narrow things down, we'll rein in our pillow talk to three types of beds, some of the most popular on the market: inner-spring, foam and air beds.

Judging from our research, there seems to be no "best" type of mattress for people with back pain or arthritis, for side sleepers or back sleepers. The best gauge is how it feels when you lie on it.

Inner-spring

This mattress has been around the longest — and it's the one people are most familiar with. The mattress's core is made of tempered steel coils, which give it that all-familiar boing-boing. The mattress is covered in layers of upholstery for insulation and cushioning. An inner-spring queen mattress can go for roughly $200 or $300 and up to $4,000 or more.

Foam

These mattresses are either made of a solid core of foam or have several layers of different foams, including latex and visco-elastic "memory" foams, like the kind in Tempur-Pedic beds — which, like most mattresses, come in various models in a wide price range ($1,200-$6,000 for a queen). Because of the special material, the mattress conforms to and supports your body and is supposed to relieve pressure that can cause pain while lying down. You'll sink down into one of these and not spring back up. These mattresses are heat-sensitive, so they can often be a little warmer than an inner-spring.

Air beds

This isn't the air mattress you bought for your first apartment. These look like a standard mattress and box spring, but instead of springs or foam, their support is air; this is the type of mattress on Select Comfort's Sleep Number bed ($1,000-$4,000 for a queen), for example. This mattress allows you to fine-tune its firmness to your needs.

Now that you know about mattress types, what new trends should you know about?

Single-sided mattress:

Remember how you never flipped your mattress every few years like you were supposed to? Ever since Simmons introduced its single-sided mattress in 2000, many of the newer mattresses are made so that you don't need to flip them. (Some experts suggest that some mattresses still be rotated from head to toe.)

More layers, more comfort:

Tod Marks says there's a big move toward increasing the amount of memory foam or latex, which provides a cushion and increases comfort. "This is certainly better than the polyester batting that we saw in years past, which has a tendency to compress and lose its loft over time, which can make for more of an indent."

Latex: So, what if you have a latex allergy — should you be concerned about buying a bed that contains latex? No, according to manufacturers and medical professionals, who say people with latex sensitivity are allergic to a protein in the latex. Manufacturers run the latex through a process that cleanses those proteins — at least that's the process used for the big S's: Sealy, Simmons, Serta and Spring Air.

A kinder, cooler memory foam:These mattresses are made with a new generation of memory foam, which keeps you cooler. We briefly tested Simmons' ComforPedic, and found it quite dreamy. Some new Tempur-Pedic models come with an "airflow system convoluted layer" — a pad that helps you stay cooler.

Outlast: Speaking of cooler, if temperature preference is crucial for you and your sleep partner, then keep the word "Outlast" at the top of your shopping list. Several mattress companies, including Serta and Select Comfort, are using Outlast technology, which adjusts the mattress to your body temperature. We tested the Sleep Number 9000 bed, and we'll be doggoned: One side was warm (and perfect for us), while the other side was cool for our partner.

Cashmere, silk, merino wool: You'll see these "luxury fabric" watchwords on more and more mattresses. Do they mean much? Not really, Marks says. "For the most part, it's a minuscule amount that's only used in the ticking — the outermost layer — which may not impact anything," he says. "It's a marketing tool; most of this stuff is meaningless."