The conversation around sleep has been dominated by duration — get your eight hours, they say — but a growing body of research suggests that position may be equally consequential for long-term health outcomes.
Side Sleeping and Brain Health
A 2024 study published in the Journal of Neuroscience found that sleeping on your side may enhance glymphatic clearance — the brain's waste-removal system that operates primarily during sleep. This system clears beta-amyloid, the protein associated with Alzheimer's disease, more efficiently when the body is in a lateral position.
Dr. Maiken Nedergaard, whose lab discovered the glymphatic system, noted that most mammals instinctively sleep on their sides, suggesting an evolutionary advantage to the position.
The Back Sleeping Paradox
Sleeping on your back is often recommended for spinal alignment, but it comes with trade-offs. Supine sleeping is associated with increased severity of sleep apnea and snoring, both of which fragment sleep architecture and reduce the restorative deep-sleep phases your body needs.
If you're a back sleeper who wakes up tired despite adequate hours, positional sleep apnea may be worth investigating with a home sleep study.
Stomach Sleeping: The Evidence
Prone sleeping puts the most strain on the cervical spine, as the head must rotate to one side for breathing. Over years, this asymmetric loading can contribute to chronic neck pain and thoracic outlet syndrome. Physical therapists generally recommend transitioning away from stomach sleeping, though the process can take weeks of adjustment.
Finding Your Position
The best sleep position is the one that lets you fall asleep and stay asleep — fragmentation matters more than position for most people. But if you have the flexibility to experiment, left-side sleeping appears to offer the most benefits: improved glymphatic drainage, reduced acid reflux, and better cardiac positioning.
A body pillow can make side sleeping more comfortable by preventing the top leg from pulling the spine out of alignment. It's a simple intervention with measurable effects on sleep quality scores.
