The Effects of Red and Blue Lights on Circadian Variations in Cortisol, Alpha Amylase, and Melatonin

Figure 2

Baseline measurements. Normalized concentration levels of melatonin, cortisol, and alpha amylase (closed symbols) measured under constant dark conditions while subjects were continuously awake for one day together with those collected during the last measurement period (open symbols) at the same clock time as for the first measurement period (08:00).