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Sleep positions under the microscope
As heatwaves push people to experiment with every possible angle, researchers are weighing the evidence on whether side, back or stomach sleeping delivers the best rest.
How scientists track sleep posture
Self-reports capture only the moments of falling asleep and waking. To fill the gap, teams have filmed volunteers overnight, attached motion sensors to limbs, and even developed infrared cameras that peer through thick blankets. A Hong Kong project, the Blanket Accommodative Sleep Posture Classification System, now maps positions without disturbing sleepers.
Danish researchers fitted sensors to thighs, upper backs and arms of adults and found that 51 % of bedtime was spent on the side, 38 % on the back and 7 % on the stomach. Older participants favoured side sleeping more strongly.
Side sleeping: the crowd favourite
Side sleeping dominates in adulthood, yet children over three divide their time evenly across all three postures. Infants are placed on their backs for safety, skewing their early habits.
A small observational study found right-side sleepers reported slightly better sleep than left-side or back sleepers. Side sleeping also reduces snoring by keeping the airway open; in some cases it has eliminated obstructive sleep apnoea altogether.
Welders on Nigerian container ships who slept on their backs experienced more back pain than side sleepers, but the benefit depends on posture. Australian researchers filmed bedrooms for 12 hours and linked "provocative side positions"-twisted spines with one thigh crossing the other-to morning neck stiffness.
Back sleeping: a mixed record
Submariners in cramped bunks often sleep on their backs, racing to doze before the cabin fills with snoring. Merchant seafarers show more respiratory disturbances when supine. Severe sleep apnoea is also more common among consistent back sleepers.
A Portuguese trial instructed older adults with back pain to sleep on their sides and those with neck pain to try their backs. After four weeks, 90 % reported reduced pain, but the sample of 20 was too small to generalise.
Left or right: the reflux divide
For acid reflux sufferers, the side matters. Sleeping on the left keeps the stomach-oesophagus junction above gastric acid, while the right side relaxes the lower oesophageal sphincter, allowing acid to escape. Doctors often recommend propped pillows, but switching to the left side may offer simpler relief.
Stomach sleeping: the outlier
Only 7 % of adults choose stomach sleeping. Studies link it to jaw pain and facial wrinkles. Plastic surgeons compare skin to "seaweed tethered to a stalk," recommending minimal strain to preserve elasticity. Face-down positions apply the most pressure, making stomach sleeping the least skin-friendly option.
Bottom line
Side sleeping appears to offer the most advantages-less snoring, fewer backaches, and reduced reflux-provided the spine stays aligned. Back sleeping can worsen apnoea and pain for some, while stomach sleeping risks jaw discomfort and wrinkles. Experts suggest experimenting with positions and keeping a sleep diary, but warn against overthinking: the quest for the perfect posture can itself keep you awake.
