Sleep positions

For most people, any comfortable position is fine. Position matters if you snore, have reflux at night, or are more than 28 weeks pregnant.

• Evidence: Some
• Low effort
• Free
• Works: tonight

Why it matters

There is no single “correct” position for everyone. We found no good evidence that back, side or stomach sleeping is better for healthy people without symptoms. Comfort and neck support matter more; see pillows.

Position does change a few things:

• Breathing. On your back, gravity pulls the tongue and soft palate toward the throat. In about half of people with obstructive sleep apnea (OSA), breathing pauses are at least twice as common on the back as on the side. A review put the average at 56% [3]. This is called positional OSA.
• Reflux. In 57 people being tested for reflux, acid stayed in the gullet for less time when they lay on their left side than on their right side or back. Acid also cleared about twice as fast on the left [5]. Lying on your right side puts the junction between stomach and gullet below the pool of stomach contents, which favours reflux [6].
• Late pregnancy. The NHS says going to sleep on your back after 28 weeks may raise the risk of stillbirth, probably because of reduced blood and oxygen flow to the baby [7].

How to do it

1. If you’re healthy and sleep well, change nothing. Pick what’s comfortable.
2. If you snore mainly on your back, try your side. A German guideline for snoring says positional treatment can be considered for people who snore only on their back [4]. A long pillow behind your back can stop you rolling over. Devices tested in trials include full-length pillows, semi-rigid backpacks, a tennis ball attached to the back of nightwear, and vibrating alarms [2].
3. If you get heartburn at night, sleep on your left side [5], and avoid sleeping right side down [6].
4. Raise the head of the bed for night-time reflux. The American College of Gastroenterology suggests this, based on several randomized trials showing less night-time acid and fewer symptoms. Raise the bed frame or use a wedge [6]. The same guideline suggests not eating within 2–3 hours of bed [6].
5. If you’re more than 28 weeks pregnant, go to sleep on your side, left or right. If you wake on your back, don’t worry; turn onto your side and go back to sleep [7]. A pillow under your bump and one between your knees can help [8].

Common mistakes

• Using side sleeping instead of a sleep study. Loud snoring with daytime sleepiness, or someone seeing you stop breathing, needs a doctor. See a doctor. The American Academy of Sleep Medicine (AASM) guideline says positional therapy should only be used as the main treatment for OSA if a sleep study shows that breathing becomes normal off your back. Not everyone’s does [1].
• Giving up on a positional device after a week of back pain. The most common side effects in trials were back and chest pain and disturbed sleep [2]. Sticking with it long term is a known problem [3].
• Panicking about waking on your back in pregnancy. The advice is about the position you go to sleep in. Just roll over [7].

Effect on your sleep score

We found no study measuring the effect of sleep position on wearable sleep scores in healthy adults.

• Wake-ups and efficiency: in people with OSA, positional therapy reduced breathing events by about 7 per hour compared with no treatment, and slightly reduced daytime sleepiness. It made no clear difference to measured sleep quality [2].
• Deep sleep, REM, HRV, resting heart rate: not measured in the studies we found.

How confident: moderate for breathing events in positional OSA; unknown for wearable metrics.

Evidence

Rated Some. For positional OSA, a Cochrane review of 8 trials (323 people) found positional therapy beat no treatment but was weaker than CPAP. CPAP lowered breathing events by about 6 more per hour. People did use positional devices about 2.5 hours a night longer than CPAP in one study. All trials were short, and the certainty of evidence was low to moderate [2]. The AASM calls positional therapy an effective secondary therapy, or an add-on, for people whose apnea is much milder off their back [1]. It isn’t a first-line treatment.

For reflux, the left-side finding comes from one observational study of 57 patients [5]. Head-of-bed elevation is a conditional recommendation based on low-quality evidence [6].

The pregnancy advice is official NHS guidance [7][8].

General information for healthy adults, not medical advice. If you have a sleep problem that lasts, read when to see a doctor. Sources checked 4 October 2026. Spot a mistake? Tell us.