Changing your sleep position takes deliberate effort, but most people can train themselves off their back within a few weeks using physical barriers, pillows, or wearable devices. The key is making back sleeping uncomfortable enough that your body learns to stay on its side, even after you fall asleep and lose conscious control of your position.
Why People Want to Stop Back Sleeping
The most common reason is snoring or sleep apnea. When you lie on your back, gravity pulls your tongue, soft palate, and surrounding tissues toward the back of your throat. This narrows your airway, and if the tissues relax enough, they vibrate (snoring) or fully block airflow (apnea). The problem isn’t just anatomy. Back sleeping also reduces lung volume and limits the ability of the muscles that normally hold your airway open to do their job.
Pregnancy is another major reason. During the third trimester, lying on your back compresses major blood vessels, reducing blood flow to the uterus. A large meta-analysis published in JAMA Network Open linked supine sleeping in late pregnancy to reduced birth weight and increased risk of late stillbirth. Public health campaigns in the UK and New Zealand now encourage women in their third trimester to fall asleep on their side.
Some people simply find that a bed partner’s nudging or their own morning grogginess tells them back sleeping isn’t working for them anymore.
The Tennis Ball Method
This is the oldest and cheapest positional therapy trick: attach a tennis ball (or a few) to the back of a shirt so that rolling onto your back becomes uncomfortable. You can sew a pocket onto the back of a snug sleep shirt, use a sock safety-pinned between the shoulder blades, or buy a purpose-built belt with a foam bump.
It works surprisingly well in the short term. In clinical testing, the tennis ball technique cut the percentage of time patients spent on their backs from around 42% of the night down to about 8%, and breathing disruptions dropped by roughly two-thirds. The problem is sticking with it. A follow-up study found that after about two and a half years, only 6% of people were still using the device. Another 13% said they had learned to avoid their back on their own and stopped needing it. But the vast majority, over 80%, had quit entirely and gone back to sleeping however felt natural. If you try this method, think of it as a training tool for a few months rather than a permanent solution.
Pillow Barriers That Keep You on Your Side
A full-length body pillow is one of the most comfortable ways to stay off your back. Hugging it keeps your top arm and leg supported, which reduces the urge to roll over. It also keeps your spine better aligned by preventing your upper knee from dropping forward and twisting your lower back. For many people, the pillow becomes a physical habit: your body associates the pillow with side sleeping, and the bulk of it behind you makes rolling onto your back less likely.
Wedge pillows are another option. Placed behind your back at a slight angle, a wedge creates a ramp that makes full supine lying uncomfortable without waking you up. A small wedge pillow between or under your knees can also relieve hip pressure, which is one of the main reasons side sleepers unconsciously flip onto their backs during the night. The more comfortable side sleeping feels, the less your body will seek out a different position.
Wearable Vibrating Devices
Electronic positional therapy devices strap to your chest or neck and deliver a gentle vibration when sensors detect you’ve rolled onto your back. The vibration is strong enough to prompt you to shift positions but not strong enough to fully wake you. These are the most studied option for people with positional sleep apnea, and compliance rates are significantly better than the tennis ball method: about 76% of users wore the device for at least four hours a night, five nights a week, compared to 42% for the tennis ball technique. At one month, compliance rates in clinical studies ranged from 92% to 96%.
The devices typically cost between $100 and $300. Some common brands include the Philips NightBalance and the Night Shift Sleep Positioner. If your doctor has diagnosed positional sleep apnea, insurance may cover part of the cost. Long-term data is still limited, but short-term results are promising, and the higher compliance suggests people find them less disruptive to sleep than a hard lump in their shirt.
Adjust Your Mattress and Setup
Side sleeping puts more concentrated pressure on your shoulder and hip than back sleeping does, so your mattress matters. If your bed is too firm, those pressure points will ache, and your body will roll onto your back to relieve them. The Sleep Foundation recommends firmness based on body weight: people under 130 pounds generally do best on a soft to medium mattress (3 to 5 on a 10-point scale), those between 130 and 230 pounds on medium to medium-firm (5 to 6), and those over 230 pounds on a firm mattress (7 to 8). If you’re currently on a very firm mattress and trying to switch to side sleeping, a mattress topper can soften the surface enough to make the position tolerable.
Your head pillow also needs to be the right height. Side sleeping creates a gap between your head and the mattress equal to the width of your shoulder. A pillow that’s too thin lets your head drop, straining your neck. One that’s too thick pushes your head up. Either way, discomfort drives you back to supine. A pillow roughly 4 to 6 inches thick works for most people, but the real test is whether your spine feels straight from tailbone to skull when you’re lying on your side.
Protect Your Shoulders and Arms
One reason people resist side sleeping is that it can cause shoulder pain or numbness in the hands. This is real and worth addressing proactively. When you sleep on your side with your elbow bent, the ulnar nerve (which runs along the inside of your elbow and controls sensation in your ring and pinky fingers) gets stretched and compressed for hours. Curling your fingers into a fist also increases pressure inside the carpal tunnel, which can cause tingling in other fingers.
The fix, according to occupational therapy researchers at Washington University, is to place a pillow in front of you that supports your entire top arm. This limits how much your elbow bends, keeps your wrist and fingers flat rather than curled, and takes weight off the shoulder you’re lying on. If you tend to sleep on the same side every night, alternating sides can prevent one shoulder from bearing all the load. Some people place a pillow behind their back and one in front, creating a “nest” that keeps them in a supported side position without pinching anything.
A Note on When Back Sleeping Is Actually Fine
Back sleeping isn’t inherently bad. A systematic review of six studies found that the supine position supports spinal alignment and is associated with lower rates of low back pain compared to stomach sleeping. Harvard Health notes that back sleepers often experience less morning neck, back, and hip pain because the position distributes weight evenly. If you don’t snore, don’t have sleep apnea, and aren’t in your third trimester of pregnancy, there may be no medical reason to change.
The people who benefit most from switching are those with positional snoring or apnea (where breathing problems are significantly worse on their back), pregnant women in the third trimester, and anyone whose doctor has specifically recommended a position change after surgery or for another condition. If you’re switching just because you read that side sleeping is “better,” weigh that against whether your current sleep is actually causing problems. The best sleep position is the one where you sleep deeply, wake up without pain, and breathe normally all night.
How Long the Transition Takes
Most people report that the first one to two weeks are the hardest. You may wake up more often, feel restless, or find yourself on your back despite your best efforts. This is normal. Your body has spent years defaulting to a position, and overriding that takes repetition. Using a physical barrier (pillow, tennis ball, or device) during this period is more effective than willpower alone, because you can’t control what you do once you’re asleep.
By three to four weeks, many people find that side sleeping starts to feel like the default, especially if the setup is comfortable. The tennis ball research showed that a small percentage of people internalized the habit well enough to maintain it without any device. Combining multiple strategies, like a body pillow plus a slightly softer mattress plus arm support, gives you the best chance of making the switch permanent rather than temporary.