Hansen, M.V., Madsen, M.T., Andersen, L.T., Hageman, I., Rasmussen, L.S., Bokmand, S., . . . Gogenur, I. (2014). Effect of melatonin on cognitive function and sleep in relation to breast cancer surgery: A randomized, double-blind, placebo-controlled trial. International Journal of Breast Cancer, 2014, 416531.
To determine the effectiveness of melatonin on postoperative cognitive function and sleep quality in women who underwent breast cancer surgery
The intervention group received 6 mg of melatonin orally one hour before bedtime one week prior to surgery through 12 weeks postoperatively. The control group received a placebo medication packaged by the hospital pharmacy with the same instructions. Both the placebo and melatonin were labeled and administered identically. Neuropsychological testing was conducted within one week preoperatively and after two and 12 weeks postoperatively. Sleep assessments were collected three days preoperatively to eight days postoperatively (short-term) and 2–12 weeks postoperatively (long-term).
Double-blinded, randomized, controlled study
There were no statistically significant differences between group characteristics. There was no evidence of cognitive impairment two weeks postoperatively in either group; however, there was a decline in cognitive performance (as a composite z-score) in the placebo group, 6.3%, compared to no decline in the intervention group (p = .38). Perioperative sleep efficiency was significantly greater for the intervention group (p = .02). Postoperative total sleep time was greater in the intervention group (p = .03). Side-effect frequency was similar for both groups; however, there was a difference in types of effects reported. Intervention side effects included dizziness (14%), headache (10%), and paresthesias (10%), and the placebo group experienced headache (27%), difficulty falling asleep (13%), and nausea (13%).
Although cognitive impairment was not found to be a significant problem in this sample, subjects who received melatonin had greater sleep efficiency and total sleep time postoperatively than those in the placebo group. In addition, subjects who received melatonin tended to have less cognitive decline although it was not statistically significant.
Melatonin may be useful as an intervention to reduce cognitive difficulties and improve sleep, but further study is warranted.