Melatonin is a hormone naturally produced in the body from the mood controlling neurotransmitter serotonin. Those suffering from serotonin deficient depression may have very low levels of melatonin and thus, sleep disruption. Melatonin regulates circadian rhythms (internal body clock) and promotes sleepiness when it is dark. A good choice if you are having problems falling or staying asleep at night. This is a subligual (dissolves under the tongue) form of Melatonin which allows for direct introduction into your system. Melatonin has also been shown to express anti-tumor and anti-metastasis effects in the treatment of some forms of cancer, including breast cancer.