Abstract
This study investigated the effect of different light intensity of the morning on dim light melatonin onset (DLMO). The subjects were 22 males (age: 20-24 years old). They were exposed to the light conditions for three hours in the morning (09:00 - 12:00). The light conditions were three light intensities (1500, 3000, 6000 lx). DLMOs were evaluated by saliva samples which were taken every 30 min from 20:00 to 1:00. The light exposures of 3000 and 6000 lx in the morning advanced the DLMOs. However, the advancing effect may depend on their lifestyle.
