Sleep one of the most fundamental and basic functions of the human body—and we spend an estimated one-third of our entire lives with our head on the pillow snoozing, yet too few of us are sleeping well, in the right sleep positions, or long enough. In fact, an estimated 1 in 3 U.S. adults is not getting their 7 to 9 hours of shut-eye each night, per data from the Centers for Disease Control and Prevention (CDC). That’s a serious problem that goes far beyond simply feeling tired and foggy during the day.

How we sleep, or our “sleep positions,” often have an impact on the quality of sleep we’re getting. And quality is just as important as quantity. Sleep positions are often based on personal preference, but are often influenced by state of health, age, comorbid disease, as well as bed partners, notes Peter Polos, M.D., Ph.D., Sleep Medicine Specialist and Sleep Number sleep expert .

Each sleep position has its own pros and cons—and a lot of these depend on the individual’s persona; medical conditions. “In patients with sleep apnea, a condition in which the soft tissues on the front of the neck fall onto the windpipe during sleep and obstruct the airway, lying flat on the back will make it worse,” says Kaliq Chang, M.D., interventional pain management specialist with Atlantic Spine Center in West Orange, New Jersey. “In patients with neck or low back pain, sleeping on the stomach may be harmful as the neck cannot be in a neutral position and the low back tends to be hyperextended (bent backwards).”

In patients without medical issues, the ideal sleep positions are simply one where the spine is the least strained. Though sleeping on the back or side is thought to be better than the stomach, Dr. Polos points out that, if the stomach works for you, then that is probably what is best.

Here’s a close look at each of the most common sleep positions and how to make the most of your night’s rest.

Sleep positions

Back (supine)

Of all the sleep positions, this is the one that provides a person the best opportunity to maintain a neutral spine throughout the night, notes Dr. Chang. For this reason, it’s the one most sleep experts recommend. It’s common for young people to sleep on their backs, however, with age, most people tend to go to one side or the other, which can be problematic for several reasons, the main being sleep apnea. “Sleeping in a supine position can worsen sleep apnea and snoring and may be a difficult position in individuals with heart failure,” warns Dr. Polos. “Note that elevation of the head can help with snoring and neck and back pain.”

Stomach (prone)

For stomach sleepers, the only comfortable way to sleep is face-down on the mattress; however, this sleep position can prove to be problematic if you suffer from back pain. If you prefer this position, though, Dr. Polos recommends against using a pillow, as to minimize the strain placed on the cervical spine. “A firmer mattress may also be beneficial, and since our sleep needs change over time, consider a smart bed with adjustable comfort and firmness on each side, particularly one that senses sleepers’ movements and automatically adjusts throughout the night to keep both sleepers comfortable,” he adds.

Side

If you’re someone who suffers from shoulder pain, this is not the best sleep position for you, as doing so may place weight on the affected shoulder. “Patients with spine injuries can maintain a neutral spine with correct position of the pillow for the neck (needs to be higher than when sleeping on the back to make sure the head doesn’t tilt left or right) or with a pillow between the knees for the low back (to keep the pelvis level),” says Dr. Chang. “Although our organs are asymmetrical, there is no absolute recommendation for which side to sleep on except for during pregnancy when the inferior vena cava, the major blood vessel returning blood to the heart, lies just to the right of the spine.”