Can melatonin improve mental side effects of chemotherapy?

This study evaluated whether melatonin could improve the side effects of chemotherapy for women with breast cancer. It found that melatonin improved sleep, depression symptoms, and clear thinking during chemotherapy.

During treatment with chemotherapy, half of the patients with breast cancer have cognitive (related to thinking and reasoning) symptoms, such as foggy thinking or worse memory. Patients with breast cancer can also have poorer sleep. Patients also experience a reduced size of a certain area of the brain, which is similar to changes during depression. Scientists believe inflammation may be responsible for these brain changes.

Melatonin is a hormone that controls sleep rhythms. The brain releases melatonin in the evening in response to dim lighting. Melatonin can also be taken as a nightly supplement. Studies have found that melatonin supplements reduce sleep disturbance and depression symptoms in patients with breast cancer and chemotherapy treatment. It is unknown whether melatonin can reduce cognitive symptoms for patients undergoing chemotherapy for breast cancer.

This study included 36 women beginning their first cycle of chemotherapy after surgery for breast cancer. Half the patients were assigned to receive melatonin for ten days, beginning three days before the chemotherapy. The other patients received placebos (inactive pills).

The patients received tests of cognitive function on the first and last days of the intervention. Patients taking melatonin had significant improvements in attention, processing speed, verbal learning, and memory compared to those taking placebo. There was no difference in sustained attention.

Patients taking melatonin also had less depression after treatment compared to before treatment. In contrast, the level of depression increased in the placebo group. The change in sleep was also significantly better for the melatonin group.

The melatonin group reported significantly reduced side effects such as nausea and pain and improved overall health after the intervention. The placebo group did not have a change in scores regarding these measurements.

This study found that melatonin supplements significantly improved quality of life during chemotherapy for breast cancer. Melatonin improved sleep quality, depression levels, and cognitive function.

This study assessed the effect of melatonin during a ten-day period around chemotherapy. Longer-term studies are needed.