Melatonin is a hormone synthesized in the pineal gland from tryptophan.It participates in several biological processes in the human being, such as circadian sleep rhythm, mood,reproductive processes and aging. Melatonin serum levels are increased in childhood and diminish importantlyin older people. Serum levels are diminished in patients with insomnia and depressive mood. Experimentally,the melatonin inhibits the growth of mammary tumors in animals. With respect to endometrial cancer andAlzheimer's disease, the information is not conclusive. No changes have been found in melatonin levelsin climacterical women. So its use has not fundament in postmenopausal women, however it can only beadministered for short periods of time for the treatment of some sleep disturbances.

Keywords: Child, Climacteric, Melatonin, Sleep Disorders