Switching to back sleeping is one of the most common sleep goals people set, and one of the hardest to stick with. Your body has spent years defaulting to whatever position feels natural, so retraining it takes a combination of physical setup, environmental changes, and patience. Most people need around two months of consistent effort before back sleeping starts to feel automatic, though the range varies widely from a few weeks to several months.
Why Back Sleeping Is Worth the Effort
Sleeping on your back distributes your weight more evenly across the widest surface area of your body, which reduces pressure points on your shoulders and hips. It also keeps your head, neck, and spine in a more neutral position compared to side or stomach sleeping. Stomach sleeping is the worst position for spinal health because it flattens your spine’s natural curves and forces your neck to rotate, often causing neck and upper back pain.
Back sleeping also keeps your face off the pillow, which reduces friction against your skin overnight. Over years, repeated compression of facial skin against a pillowcase contributes to sleep wrinkles, so supine sleeping is one of the few positions dermatologists recommend for skin health. If you deal with acid reflux, back sleeping with your head slightly elevated can also help keep stomach acid from traveling upward.
Set Up Your Bed for Back Sleeping
The right pillow and mattress make the difference between a position that feels comfortable enough to maintain and one you abandon by 2 a.m. For your head, you want a medium-loft pillow, typically 3 to 6 inches thick. This height supports the natural curve of your neck without pushing your head too far forward. A pillow that’s too thick angles your chin toward your chest, straining your neck. Too flat, and your head drops back, creating tension at the base of your skull.
Place a second pillow under your knees. The Mayo Clinic recommends this specifically because it helps relax your back muscles and maintain the natural curve of your lower back. Without it, your legs lie flat and pull your pelvis forward, creating a gap between your lower back and the mattress that leads to stiffness and soreness by morning. A rolled-up towel works if you don’t have an extra pillow, but a knee pillow shaped like a half-cylinder stays in place better.
Your mattress matters too. Back sleepers generally do best on a medium-firm surface, around 6 to 7 on the standard 1-to-10 firmness scale. If you weigh under 130 pounds, a medium firmness (around 5) provides enough contouring without letting your hips sink too deep. Between 130 and 230 pounds, aim for a 6 to 6.5. Over 230 pounds, a firmer 7 keeps your spine aligned. A mattress that’s too soft lets your hips drop below your shoulders, and one that’s too firm creates pressure points that will send you rolling to your side.
Physical Barriers That Prevent Rolling
The biggest challenge isn’t falling asleep on your back. It’s staying there. Most people roll to their side or stomach unconsciously during the night, often within the first hour. Physical barriers give your body a reason not to roll.
The simplest approach is placing firm pillows on either side of your torso, from your ribs to your hips. These create a “bumper lane” effect. When your body tries to turn, it meets resistance and settles back. Some people use rolled-up towels or even pool noodles tucked under a fitted sheet for the same purpose.
You may have heard of the tennis ball technique, where you attach a tennis ball to the back of your pajama top to discourage lying on your back. That method is traditionally used in reverse, for people with sleep apnea who need to avoid back sleeping. But the same principle works in any direction. Taping or sewing tennis balls to the sides of a snug sleep shirt creates discomfort when you roll, training your body to stay supine. The limitation: up to 25% of people still manage to shift positions despite the obstacle, and the balls can migrate during the night.
There are also wearable devices designed for positional sleep training. Some clip onto your pajamas or attach to your neck and vibrate gently when they detect you’ve shifted off your back. The vibration is subtle enough to redirect you without fully waking you up.
A Nightly Routine That Builds the Habit
Research from University College London found that forming a new habit takes an average of 66 days, with individual timelines ranging from 18 to 254 days depending on the person and the complexity of the behavior. Sleep position is on the harder end of that spectrum because you’re trying to control something that happens while you’re unconscious. Expect to spend at least two to three months actively working on this before it becomes your default.
Start by spending the last 10 to 15 minutes before sleep lying on your back with your setup in place: knee pillow, medium-loft head pillow, side barriers. Use this time to do a body scan or breathing exercise. Focusing on relaxing each muscle group from your feet upward does two things: it associates the back position with your wind-down routine, and it helps you fall asleep faster in a position that might initially feel unfamiliar.
If you wake up on your side or stomach during the night, don’t stress about it. Just reposition yourself on your back and resettle. The first few weeks, you might do this three or four times a night. That frequency drops as your body adapts. Some people find it helpful to set a single, gentle alarm midway through the night for the first week or two as a position check, though this disrupts sleep and isn’t worth continuing long-term.
Consistency matters more than perfection. Sleeping on your back for even the first few hours each night trains your body over time. You don’t need to maintain the position for a full eight hours from day one.
When Back Sleeping Isn’t Safe
Two groups of people should avoid training themselves to sleep on their back: those with obstructive sleep apnea and those in late pregnancy.
For people with sleep apnea, lying on your back allows gravity to pull the tongue and soft tissues of the throat downward, partially or fully blocking the airway. In positional sleep apnea, the number of breathing interruptions per hour is at least twice as high in the back position compared to sleeping on your side. The supine position also worsens the severity of each event: episodes last longer, oxygen levels drop further, and heart rate fluctuations become more pronounced. If you snore heavily, wake up gasping, or have been told you stop breathing during sleep, talk to a sleep specialist before attempting to train yourself into back sleeping.
For pregnant women, back sleeping becomes risky in the third trimester, particularly after 37 weeks. A New Zealand case-control study found that going to sleep on the back was associated with a 3.7 times higher risk of late stillbirth, and at term the risk was even more pronounced at roughly 10 times higher. The likely mechanism is that the weight of the uterus compresses a major blood vessel that returns blood to the heart, reducing blood flow to both the mother and baby. Side sleeping, especially on the left, is the recommended position from 28 weeks onward.
What to Do if It Still Feels Uncomfortable
Some discomfort in the first week or two is normal. Your muscles are accustomed to a different position, and it takes time for them to relax in a new one. If your lower back aches, experiment with the height of your knee pillow. A thicker pillow creates a deeper bend at the knees, which tilts the pelvis and takes more tension off the lumbar spine. If your shoulders feel stiff, make sure your mattress has enough give to let your shoulder blades settle slightly into the surface rather than sitting on top of it.
People with broader shoulders or larger body frames sometimes find that a thin pillow under each arm, in addition to the side barriers, prevents their arms from falling outward and pulling on the shoulder joints. Placing your arms at your sides with palms up, or resting your hands on your stomach, are both neutral positions that reduce shoulder strain.
If you’ve been trying for several weeks and still can’t fall asleep on your back at all, a transitional approach can help. Start on your back and give yourself 20 minutes. If sleep hasn’t come, roll to your preferred side position and allow yourself to drift off. Over time, gradually extend that initial back-sleeping window. Your body will begin associating the position with drowsiness, and the transition period shortens naturally.