Who/What It's Bad For:
While sleeping face up helps keep wrinkles at bay, it's not the perfect position for sleepers with sinus issues such as allergies, sinus headaches, snoring or sleep apnea. "If you already have sinus problems, sleeping on your back will only push existing drainage up your sinuses further and increase pain," says Dr. Breus. All of that mucus (apologies for the graphic mental image) falls to the back of the throat as you're sleeping, which can cause you to wake up frequently with coughing attacks. Rather than try to switch sleeping positions (a nearly impossible task), Dr. Breus recommends trying to treat your allergies or sleep apnea first. Sleeping on your back is still ideal, mucus aside.

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Board certified spine surgeon Dr. Hooman Melamed, MD, who's been featured on "The Doctors," "The Steve Hardy Show" and "Dr. Oz," suggests choosing a mattress with plenty of support that allows you to sink into it. "Memory foam reduces stress on pressure points and is good for the spine (and helps absorb movement if your partner is a restless sleeper). Latex mattresses are another good option, and if you want to save money, latex toppers are available." Although they seem quite messy (and a little '70s), waterbeds are also ideal for back sleepers.

Sleep Ranking: Bad news ...

Who/What It's Good For:
Sleeping on your stomach isn't necessarily good for anyone. If you have problems with your sinuses or allergies and really can't sleep on your back, it's better to try sleeping on your side than snoozing on your stomach (the transition is also easier).

Who/What It's Bad For:
Sleeping on your stomach comes with an entire list of problems, from more wrinkles to increased neck pain. But keep reading! There are subtle changes you can make to transition into a different position. "Waking up in pain is the clearest indication it's time to change your sleep position," says Dr. Breus. And if you're sleeping on your stomach, you're bound to experience neck pain, because the position keeps your neck turned at an almost 90-degree angle, straining the muscles.

Sleeping on your stomach is also the No. 1 worst position in terms of wrinkles and aging. The pressure of your face pressing into your pillow will lead to more fine lines, in addition to puffiness around the eyes. "When you sleep on your stomach, your head is at the level of your heart, especially if you sleep with a flatter pillow, so you are going to get much more blood flow to your face," says Dr. Day. However, it's also important to remember that your lifestyle still plays into aging. "Sun protection is important no matter what position you're sleeping in. The sun is what's breaking down the collagen in your skin. If you sleep on your stomach but you're someone who never goes out in the sun, you're going to be less likely to get that sleep wrinkle." For a gentler night's sleep on your skin, it's worth investing in a higher thread count or satin pillowcase to avoid chafing.

Try This:
If you're a chronic stomach sleeper, it's easier to transition to sleeping on your side than it is to your back. Dr. Breus suggests wearing two t-shirts to bed. Between the two shirts, rest a football on your stomach. The football will keep you from comfortably rolling onto your stomach and should help you naturally transition to side sleeping in seven to ten days. But if sleeping with a football seems a little, er ... inconvenient, try sleeping with a body pillow (or partaking in some spooning.) "Holding the object close will keep you from rolling forward onto your face and stomach, but you'll still feel as though you're sleeping in a forward position," says Dr. Day.

If all else fails and you still find yourself facedown each night, Dr. Melamed recommends a firm mattress to support the natural curve of your spine and to keep you from over-arching.

Sleep Ranking: Eh, at least you're not sleeping on your face

Who/What It's Good For:
If you're pregnant, have heartburn or sinus issues (or simply can't sleep staring straight at the ceiling), it's best to sleep on your side. "The left side is best for heartburn or acid reflux, because the position keeps your stomach below your esophagus," says Dr. Breus. A side sleeping position also keeps your tongue from falling to the back of your throat, which causes you to snore. Pregnant women may find side sleeping can improve blood flow and the amount of nutrients being delivered to the baby, as well as reduce swelling in their hands, feet and ankles (of course a killer high heel obsession a la Kim Kardashian will probably undo all of those benefits).

Who/What It's Bad For:
The good news -- 75 percent of Americans sleep on their side, according to Dr. Breus, so although it's not quite as good as sleeping on your back, it's perfectly fine to continue snoozing on your side. The bad news: Dr. Day says side sleepers often get wrinkles or creases on the side they naturally turn to in sleep, getting a deeper crease on the side they favor. If you can't break out of the fetal position, Dr. Melamed recommends choosing a softer mattress. The mattress should help you avoid pressure points, but shouldn't be so soft that it doesn't properly support your neck.

Try This:
Because transitioning to another sleep position is so difficult, Dr. Breus says staying put sleeping on your side is perfectly fine. But if you simply can't settle for less than the optimum (sometimes our perfectionist can't help but kick in), proper pillow placement can help you transition to sleeping on your back. Many side-sleepers attempt to use pillows under their knees or on either side to keep them from rolling over, but this won't work as well as you'd imagine. "We often see that people will fall asleep on their back, and then roll over on top of these pillows meant to keep them on their back," says Dr. Breus. "Instead take couch cushions (the big ones you sit on) and put them on either side of your torso. These pillows are large enough to keep you on your back and won't easily roll out of position."