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. 2013 Aug 1;36(8):1239–1246. doi: 10.5665/sleep.2894

Figure 2.

Figure 2

Effects of different illuminance histories on the alerting response to a 90-lux light exposure. Subjective sleepiness (derived from visual analog scale), attentional lapses (derived from the psychomotor vigilance task, PVT), EEG delta/theta activity (power density in the 2.0-5.5 Hz range), and plasma melatonin levels are shown before, during, and after a 90-lux light exposure (LE). The LE started 1 h before habitual bedtime. The open and filled symbols/bars denote 90-lux history and 1-lux history conditions, respectively. Significant differences of the interaction Condition × Time are shown in panels B, C, and D (2-way ANCOVA with Circadian Phase Angle as a covariate). Asterisks denote significant results for planned comparisons between conditions (P < 0.05, paired t-tests).