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.
Sleep loss is a common problem after surgery.
The researchers examined whether melatonin levels were also low on the first night after surgery. We found that melatonin levels were very low the night after surgery. The study was done in seven women between the ages of 32 and 49. All were patients at Penn State Milton S. Hershey Medical Center. Cronin explained that the timing of the body's internal clock, which controls circadian rhythms such as sleep, is reflected by melatonin levels.