Fig. 1From: Can tryptophan supplement intake at breakfast enhance melatonin secretion at night?The experimental protocol. Horizontal bars indicate experimental light conditions; gray, black, and white represent dim (<50Â lx), dark (0Â lx), and bright (>5000Â lx) lights, respectively. Arrows indicate the times of data collection; gray and white arrows indicate saliva and urine collection times, respectively. Gray triangles show the times of mealsBack to article page