ABSTRACT
The melatonin rhythm is generated by an endogenous clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus.
The melatonin secretion phase is entrained to the dark period, and it can be acutely suppressed by light exposure during the night. There are reports that melatonin inhibition occurs even under low light intensity.1,2 In 1980, Lewy et al.3 demonstrated that melatonin secretion in humans could be inhibited by arti£cial light of suf£cient intensity and duration. A dose-dependent effect of the suppression was observed between 500 and 2500 lux given for 2 hours from 0200 to 0400 h. In addition, the bright light acutely affected the core body temperature (Tcore) rhythm.4 Even in adolescent
23.1 Introduction .......................................................................................................................... 365 23.1.1 Nighttime Melatonin Production Suppressed by Light ............................................ 365 23.1.2 In—uence of Diurnal Bright/Dim Light Exposure on Melatonin Production ...........366 23.1.3 Lights with Various Wavelengths Affecting Melatonin Production.........................366
