Melatonin Rhythm in Human Plasma Saliva

Abstract

Human plasma saliva were collected at frequent intervals throughout the night after a nocturnal challenge by exposure to 3,000 Ix of light for 1 h in the middle of the night. Melatonin, as measured by radioimmunoassay, was found to correlate highly in plasma saliva, described by a linear regression equation: y = 55x ‐ 2.6 (r = 0.90). The nocturnal melatonin rhythm in saliva was parallel to that observed in plasma. A good correlation was also observed between plasma salivary melatonin on exposure to light. Melatonin in both fluids showed a significant fall during light exposure. Levels returned to normal nocturnal values within 2 h after returning to darkness. These results indicate that sali..