Abnormal Circadian Melatonin Secretion in Night-Shift Workers

Abstract

To the Editor: The pineal hormone melatonin, owing to the direct suppressant¹ and entraining² effects exerted on its production by light, is secreted in a circadian fashion, so that there are low levels during the day and high levels at night. This typical secretion pattern is observed without exception in all mammalian species, irrespective of whether the animal is active during the light or dark part of the day.³ In humans, too, the period of elevated melatonin secretion occurs at night, although a shift of this period toward dusk^{4 , 5} or dawn⁶ has been observed in several persons. This peculiarity of . . .