Sleeping on your side is healthy for most people and offers several specific advantages, particularly for breathing and digestion. Around 65% of people naturally sleep in a lateral position, making it the most common sleep posture by a wide margin. That said, side sleeping does come with trade-offs for your joints and skin, and small adjustments can make a meaningful difference in how well it works for you.
Why Side Sleeping Helps You Breathe Better
The clearest benefit of side sleeping is that it keeps your airway open. When you lie on your back, gravity pulls the tongue and soft tissues toward the back of the throat, partially blocking airflow. On your side, those tissues stay out of the way, which reduces snoring and can significantly improve obstructive sleep apnea. For people with positional sleep apnea, where breathing disruptions are worse in certain positions, switching to lateral sleep is sometimes enough to bring symptoms under control without other interventions.
Left Side vs. Right Side
The two sides aren’t identical. Each has distinct advantages depending on your health concerns.
Sleeping on your left side appears to help with acid reflux. A study of 57 people with chronic heartburn found that while stomach acid entered the esophagus at roughly the same rate regardless of position, it cleared much faster when participants lay on their left side compared to their back or right side. Faster clearance means less tissue damage over time and less pain during the night. If you deal with heartburn, left-side sleeping combined with elevating your upper body is one of the most practical things you can try.
Sleeping on your right side may offer a slight cardiovascular edge. When you lie on your right, the heart sits slightly elevated, which can facilitate blood pumping and venous return. This position tends to reduce sympathetic nervous system activity, essentially dialing down your body’s stress response during sleep. For most healthy people, this difference is subtle, but it’s one reason you’ll sometimes see conflicting advice about which side is “best.”
Brain Waste Clearance During Sleep
Your brain has its own waste-removal system that operates primarily during sleep, flushing out metabolic byproducts including proteins associated with neurodegenerative disease. Research published in the Journal of Neuroscience found that this system worked most efficiently in the lateral sleeping position compared to sleeping on the back or stomach. The mechanisms are complex, involving changes in blood flow, arterial pulsing, and nervous system activity that shift with body position. While this research was conducted in animals and hasn’t been fully confirmed in humans, it aligns with an interesting observation: lateral sleeping is the default rest position for most mammals.
Joint Pain and Pressure Points
Side sleeping’s biggest drawback is the pressure it puts on your shoulders and hips. Your spine doesn’t naturally stay aligned when you’re on your side, and the weight of your body concentrates on a relatively small contact area. This can aggravate existing problems in the neck, back, and hips.
Hip pain from side sleeping is especially common. Lying on an arthritic or inflamed hip compresses the joint directly. But even sleeping on the opposite side can cause problems, because the affected hip tends to fall forward, straining the joint in a different way. If you have bursitis, arthritis, or a hip injury, neither side may feel comfortable without some modification.
Shoulder problems follow a similar pattern. The shoulder bearing your weight gets compressed against the mattress for hours, which can worsen impingement or rotator cuff irritation. People with shoulder pain often find themselves switching sides throughout the night, which can disrupt sleep quality.
How to Align Your Spine on Your Side
The joint issues associated with side sleeping are largely fixable with proper support. The goal is to keep your hips, spine, and neck in a neutral line rather than letting them sag or twist.
- Between the knees: A pillow between your legs keeps your hips aligned and prevents the top leg from pulling your pelvis forward. Orthopedic specialists routinely recommend this for anyone with hip arthritis or bursitis.
- Under your head: Your pillow should be thick enough to fill the gap between your shoulder and ear so your neck stays straight. Too thin and your head drops; too thick and it tilts upward.
- Under your belly (pregnancy): During the second and third trimesters, side sleeping is the recommended position. A pillow under the belly and between the knees helps support the extra weight. Full-length body pillows work well here.
Mattress firmness matters too. Side sleepers need enough cushion for their shoulders and hips to sink in slightly, keeping the spine level. If you weigh under 130 pounds, a soft to medium mattress (around 3 to 5 on a 10-point firmness scale) works best. Between 130 and 230 pounds, aim for medium to medium-firm (5 to 6). Over 230 pounds, a firmer mattress (7 to 8) provides the support needed to prevent excessive sinking.
Effects on Your Skin
Side sleeping does contribute to facial wrinkles over time. The mechanical compression of your face against a pillow creates “sleep wrinkles” that are distinct from expression lines. These tend to appear on the forehead, lips, and cheeks, and they typically run perpendicular to the wrinkles caused by smiling or squinting. Because they’re caused by physical pressure rather than muscle contractions, Botox doesn’t help with them.
Sleeping on your back eliminates this issue entirely, but given how difficult it is to consciously change your sleep position, this is more of a cosmetic trade-off to be aware of than a compelling reason to overhaul your habits. Silk or satin pillowcases can reduce friction and may slow the process somewhat.
Eye Pressure and Glaucoma
For people with glaucoma or elevated eye pressure, side sleeping introduces a specific concern. Lying on one side tends to raise intraocular pressure in the eye closest to the pillow. If you consistently sleep on the same side, the eye on that side gets more sustained pressure exposure throughout the night. One study found that sleeping with the head elevated on a 30-degree wedge pillow significantly lowered nighttime eye pressure compared to lying flat. If you have glaucoma that’s progressing despite good pressure readings at the doctor’s office, alternating sides or elevating your head may be worth considering.
Who Benefits Most From Side Sleeping
Side sleeping is particularly valuable for people who snore, have sleep apnea, experience acid reflux, or are in the later stages of pregnancy. For these groups, it’s not just a comfortable preference but a genuinely healthier position. People with hip or shoulder problems can often make it work with proper pillow placement and the right mattress. The skin effects are real but slow-developing and cosmetic. Overall, if you’re a natural side sleeper, you’re already in the position that works best for the majority of people.