Sleepers, Awake! Position IS Everything in Life!

Cats and dogs curl up to sleep tight. Humans do too, most commonly in a position that the snooze experts at the Harvard Women’s Health Watch say is shaped by their age, size, weight, mattress, pillows, and whether they share a bed. Last month, having carefully run through the relevant studies, the website for the Sleep Foundation team of specialists who deliver science-backed sleep-health news rated the four most popular ones.

First the bad news: Sleeping on the tummy is a bummer. Start with the fact that while stomach-sleeping may reduce snoring, its simple gravity pushes the torso deeper into the mattress, arching the back and pushing the spine up as well. The resulting strain causes an aching neck made more so by the repeated need to turn the head to breathe.

Turning over is a mixed bag. For example, one study of sleepers with back pain found that those who switched to back-sleeping reported significantly less discomfort because the spine stays straighter, an effect the sleeper may heighten by siding a pillow under the lower back. But as John Winkelman, a professor of psychiatry in the Division of Sleep Medicine at Harvard Medical School, says, back-sleeping can intensify problems for people who snore or have sleep apnea or other breathing challenges.

“All the soft tissue in the back of the throat falls back like a cork. Gravity is not our friend here.” Similarly, sleeping on one’s back may make it difficult to expand the lungs, one reason why people with heart failure or lung problems may feel short of breath if they sleep on their back. In Winkelman’s words: “It can feel a little like someone sitting on your chest.” Finally, given the position of the back of the throat and the tube (esophagus) that sends food down to the stomach, sleeping flat on the back can make it easier for stomach acid to back up into the esophagus, perhaps causing acid reflux strong enough to wake even the deepest sleeper.

Surprisingly, most people seem instinctively to know these front and back facts because the scientific data show that more than 60 percent of male and female adults sleep on their side, making this often the best choice for relieving back pain and reducing sleep apnea symptoms. Side-sleeping also helps to keep airways open, a benefit not just for the sleeper but for any partner as well because doing that reduces snoring. But as noted, the sides—left and right—are not complete equal. Sleep-health people recommend left-side rest because in addition to facilitating acid reflux, right-side sleeping puts pressure on the liver as well as the vein that carries blood from the legs back to the heart.

In the end, it’s a guess how any one person will choose to sleep, and, position aside, how the entire night will go. As Dr. Winkelman says, “I’ve interpreted thousands of sleep studies, and rarely do you see someone sleeping in the same position all night long. We all have 90-minute sleep cycles, and when we change sleep stages, we often punctuate those shifts with a position change.”