Sleep loss is a common problem after surgery.
The researchers examined whether melatonin levels were also low on the first night after surgery. Melatonin is a hormone made by the pineal gland in the brain. Each day as evening comes the pineal gland goes to work, releasing into the bloodstream increasing amounts of melatonin, peaking between 2 a.m. and 4 a.m. Although melatonin's effects aren't well understood, the hormone may play a role in many body processes. We found that melatonin levels were very low the night after surgery.