Figure 2: Normalized morning cortisol levels during the Dim Light Session and during the two blue light exposure sessions. All data were normalized to levels gathered at the first, common experimental sampling time of 6:00 AM, which was the time of awakening. Shown are the mean ± SEM normalized cortisol levels for each experimental condition and sample collection time; normalized cortisol levels during blue light exposures that were significantly different than those during dim light are indicated with asterisks.