Sleep positions go by countless creative names — the zombie, mountain climber, free faller, and soldier — yet sleep experts typically simplify them into four basic types: left side, right side, stomach, or back. Until the age of one, it is recommended that babies sleep on their backs to lower their risk of choking and suffocation. As young children, we start to move around more in our sleep, usually ending up on our sides and backs. And this tendency to avoid sleeping on our stomachs only grows with age.
By adulthood, most people prefer side-sleeping, while fewer favor back-sleeping, and stomach-sleeping is the least preferred overall. But of course, individual sleep styles are highly personal: some people are sworn belly sleepers, while others can't nod off unless they're sprawled out on their backs.
How we spend the night affects our bodies in several ways. Different sleep postures shift the relative positions of our internal organs, which can either relieve or worsen certain health issues. Others can leave the spine unsupported, straining nearby tissue, and preventing the muscles in the back, hips, or neck from fully relaxing. This can then lead to tension and stiffness in the morning.
Take, for example, the least popular position: sleeping prone. Of the four, this also tends to be the least recommended by sleep experts, as it's thought to stretch the natural curvature of your spine. Yet there are unique situations when lying on your stomach may be beneficial. For patients with certain respiratory conditions, for example, it allows the back of the lungs to expand more freely.
Sleeping on your back, on the other hand, is often preferred by those with lower back pain. When paired with a small pillow under the knees, this position allows the spine to maintain its natural curve. However, it may be less than ideal for your sleep partner. For some people, lying on their back can cause the soft tissues of the throat and tongue to collapse into the airway. Then, as the body tries to pull air through, these tissues vibrate, creating the sound we call snoring. This is also why people with sleep apnea are often told to avoid this position. This condition already involves pauses in breathing, and back sleeping can increase the likelihood that the airway collapses completely, blocking airflow.
Today, most experts generally recommend side-sleeping, particularly when combined with a pillow between the knees, to better align the spine. But as it turns out, which side you lie on may make a difference. For example, studies show that sleeping on the left side often reduces heartburn symptoms for those with acid reflux. Your stomach is primarily located on the left side of your body, so this position situates it below the esophagus, allowing gravity to naturally keep stomach acid from flowing back up. However, for people with congestive heart failure, who often have an enlarged left ventricle, sleeping on the right side can help relieve chest pressure and improve their overall quality of sleep.
Clearly, there's no one-size-fits-all answer. And attempting to reap the benefits of any one position can be tough, since most people shift positions 20 to 30 times per night without even knowing it. Pillows and other sleep training devices can help you stay in one place. But fortunately, unless you have a specific concern, sleep movement isn't always a bad thing. It's how your body naturally relieves pressure, responds to discomfort, and ultimately prevents injury.
So, the next time you find yourself drifting to the free faller, soldier, or zombie, you can rest assured.