Scientists have attributed the health benefits of red wine to its high content of the polyphenol resveratrol.  A South African study on rats found that melatonin in wine might be a better explanation for the health benefits of red wine. Melatonin is a hormone produced by the pineal gland in the brain that promotes sleep. It is produced cyclically in response to darkness and light. Melatonin protects the heart from chemicals called free radicals that promote heart stress. Supplementing the hormone might be a lifesaver during a heart attack when a hear is not getting enough oxygen.