A 2026 study of 161 men with male-pattern hair loss found greater recession on their usual sleeping side, but experts say it does not prove side-sleeping causes baldness. They say pillow friction can break hair, especially when it is wet or damaged.
Researchers measured recession on each side of participants’ hairlines, not the amount of hair they lost overall; men also self-reported which side they slept on. The study authors speculated that prolonged pressure could reduce blood flow to follicles, but a hair-transplant surgeon said pillow pressure is not enough to stop it.
Experts say friction-related breakage is more likely in wet or already damaged hair. Satin or silk pillowcases and bonnets may reduce rubbing, while tight wraps or hair ties can add traction. Smoother fabrics are not a treatment for androgenetic alopecia, or patterned hair loss.
