Confusion after surgery is often delirium, a sudden change in brain function that makes a person confused and disoriented. It is more common in older adults, and the risk goes up with age, poor health, memory problems, dementia, many medicines, poor hearing or eyesight, and emergency surgery. It can start soon after anesthesia or a few days later. It may come and go, and symptoms are often worse in the evening or at night.

Delirium can look different from person to person. Some people are quiet and very sleepy. Others are agitated, shout, or try to get out of bed. They may not know where they are, not recognize family, or see or hear things that are not there. It can last hours to days, and sometimes longer.

The hospital team usually looks for and treats the cause, such as pain, infection, constipation, dehydration, or medicines that may be adding to the confusion. They may also help with glasses, hearing aids, daylight, a regular routine, sleep, fluids, and family support.