Last reviewed: September 29, 2026

Probably sooner than many people are told. Sleeping only on the back is one of the traditional hip precautions, and patients rate it the hardest one to follow.

In a trial of about 400 people whose hip was replaced through the back of the hip, people allowed to sleep in any position dislocated no more often in the first eight weeks than people told to sleep only on their back. Their pain and function were the same. In an earlier trial where the hip was replaced through the front and side, people allowed to sleep on their side, and freed from several other rules, went back to side-sleeping sooner and were more satisfied. Dislocation was rare in both groups. A review of these trials rated the overall evidence on precautions as very low quality.

Some things have not been studied. No study has compared lying on the operated side with lying on the other side, or tested a pillow between the knees on its own. The trials were in first-time replacements, not redo operations.

According to the American Academy of Orthopaedic Surgeons, when precautions for sitting, bending or sleeping are given, they usually last about the first six weeks.

Sleep itself may be no better, or a little worse, for the first few weeks. By three to six months, many people sleep better than before surgery, and hip patients were more likely to improve than knee patients.

In general:

  • Follow your own surgeon’s instructions. They reflect how your hip was put in.
  • If sleeping on your back is keeping you awake, ask whether you still need to.
  • A redo operation, or a hip that has dislocated before, is a different question.
  • Poor sleep that is not improving after the first months is worth mentioning to your physician.

Drafted with AI assistance from published sources, reviewed and edited by Babak Sheikh, MD.

Sources:

This is general information about what published research shows. It is not medical advice and it is not about your situation. Reading it does not create a doctor-patient relationship with me. I am a retired orthopedic surgeon and I do not see patients. Talk with your own doctor before changing anything about your care. If something feels suddenly or seriously wrong, get medical care promptly rather than waiting.

This page is provided as is. I make no guarantee that it is accurate, complete or current, and medical evidence changes. Use of it is at your own risk.

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