The majority of people sleep on their side—an idea that has been corroborated by a number of sleep studies. In fact, researchers in the Danish Physical Activity Cohort with Objective Measurements (DPHACTO) study—one of the largest sleep studies conducted in the world—found that sleepers spent over half (54.1%) of total time in bed sleeping on their side.
Side sleeping can cause or exacerbate shoulder and neck pain, and contribute to muscle imbalance. Therefore, side sleepers need to be aware of their neck and shoulder alignment to avoid waking up with body aches.
This article explains how to get the most out of side-sleeping while avoiding serious injury.
Benefits of Being a Side Sleeper
Pain
Sleeping on your side is good for spine alignment. It may alleviate pressure on your back that can cause or exacerbate back pain. Sleeping with a pillow in between your knees has also been shown to be an effective way to treat hip and knee issues.
Digestion
While there’s no empirical evidence that supports the idea that sleeping on one side or the other is more effective in aiding digestion, there is enough research supporting left-sided sleeping as a digestive aid that it can’t be ruled out. Still, most evidence is anecdotal, and more research needs to be done.
Brain Health
Early research points to side sleeping as a potential way to improve brain functioning and achieve optimal brain functioning. Preliminary research, primarily in animals, shows that side sleeping may aid in the removal of toxins from the brain and may even reduce the risk of neurological disease.
Brain waste leaves through the glymphatic system. Cleansing of the glymphatic system occurs when you’re sleeping.
Side sleeping appears to maximize the cleansing process, which is important given the role of brain waste in the development of Alzheimer’s disease and other neurodegenerative diseases. Still, more research, particularly human trials, needs to be done to corroborate these early findings.
Sleep Apnea
If you wake up breathless or have poor sleep quality that makes you feel tired during the day you might have obstructive sleep apnea (OSA).
OSA is a sleep disorder that occurs when the muscles of the upper airway relax, narrowing or closing the airway, momentarily cutting off breathing. The most common causes of OSA and situations that may exacerbate it are:
Being overweight or obese (including a large neck size) Abnormal upper airway anatomy (including a deviated septum) Using medications, drugs, or alcohol Aging Sleeping on your back REM or dreaming sleep Smoking
Sleeping on your back allows the muscles that support the soft tissues in your throat, such as your tongue and soft palate, to temporarily relax thanks to gravity. As a result, you may develop common OSA symptoms like loud and chronic snoring, choking or gasping during sleep, and frequent nighttime awakenings or insomnia.
Sleeping on your side keeps your airways open. Therefore, it’s a preventative strategy that may alleviate your symptoms and improve the quality of your sleep.
Pregnancy
During the second and third trimesters of pregnancy, some healthcare providers might suggest sleeping on your left side with your knees bent in a comfortable position. This posture may help improve circulation to the heart and allow for the best blood flow to the fetus, uterus, and kidneys. Of note, sleeping on your left side alleviates pressure on your liver because this position keeps the uterus off that large organ.
Side Sleepers Positions
Side sleeping usually occurs in one of three positions:
Fetal: The fetal position, which is the most common side sleeping position, is when people are curled up in a ball similar to a fetus in the womb. Log: In this position, your legs are extended and your arms straight down, erect just like a log. This is the second most common side sleeping position. Yearner: In the yearner position, your legs are extended like the log position but your arms are extended like you’re reaching for something. This is the least common side sleeping position.
How to Sleep Comfortably
Sleeping on your side is a comfortable way for many people to sleep, which explains why half of your sleep is on the side. Maintaining proper spinal alignment by using the right pillow at the right height and laying on a medium to medium-firm mattress usually leads to the most comfortable sleep.
If you have GERD, you may want to avoid sleeping on your right side, and if you experience shoulder pain, you might want to avoid sleeping on the side that hurts or your side altogether.
Which Side to Sleep On
Heartburn and Side Sleeping
If heartburn is keeping you up at night, you may want to turn over to your left side. Some studies have found that sleeping on the right side can aggravate heartburn, while sleeping on your left may calm it.
The reason is not entirely clear, but some researchers hypothesize that right-side sleeping may relax the lower esophageal sphincter, between the stomach and the esophagus, allowing for stomach acid to reflux.
Signs You’re Not a Side Sleeper
It’s hard to know whether or not you’re a side sleeper because the position you fall asleep in is not necessarily the position you wake up in. However, there are some tell-tale signs that you sleep on your back more than your side.
You might be being tired all day long because sleeping on your back can collapse the upper airway. This causes you to snore loudly or wake up feeling breathless, signs of obstructive sleep apnea (which requires a medical evaluation to confirm a diagnosis).
If you experience symptoms of acid reflux, it may also be a sign that you’re sleeping on your back. You may want to elevate your head and torso to relieve symptoms.
Best Sleep System for Side Sleepers
Mattress
Picking the right mattress is important for everybody, but it’s especially important for side sleepers because one side of your body is bearing all your weight. It’s probably best not to have a mattress that is too soft or too firm. A medium to medium-firm mattress can help support heavier parts of the body without causing pressure buildup at the hips and shoulders.
Pillow
If you sleep on your side, you might notice that it’s hard to keep your head aligned with your spine using one standard pillow. Using two pillows or a thicker therapeutic pillow is best to keep your head aligned with the rest of the spine.
Summary
Side sleeping offers many health benefits, from better spine alignment to reduced snoring. It also reduces GERD symptoms and is the preferred position for pregnant women and people with heart failure.
A Word From Verywell
Side sleeping may have some important health benefits, but it’s important to take all this new information that is gathered into context.
If you have sleep apnea, for example, side sleeping is just one way to help alleviate your symptoms, but it should not be the only treatment method that you use. Also, shifting positions is a natural part of sleeping that you can’t control. Thus, just because you commit to falling asleep on your side doesn’t mean that you will stay there.
Placing a pillow underneath your kneesPlacing a pillow under your lower back Creating a fortress of pillows around yourself.
Of note, some people find that back sleeping increases discomfort in their lower back, but prefer to sleep on their back anyway. In this case, placing a pillow under your lower back while you sleep might help.
