Can I wear the knee support overnight or for long periods?

The product description is about use during movement: sport, exercise, physically active work, and recovery periods after a minor strain or plaster cast removal. There is no statement that it is intended for overnight use. During sleep, the leg moves much less, so the two main effects of the sleeve, compression and warmth, have little practical job to do. Wearing a neoprene sleeve for many hours can also make skin sweat and increase the chance of irritation, especially behind the knee.

If you are considering long wear, the most important point is how the sleeve feels. A sleeve that leaves deep red grooves, causes tingling, or feels tighter as the day goes on is too restrictive. Take it off and give the skin a break. For any nighttime use or prolonged daily use, ask a medical professional first. The product is not a replacement for professional advice.