Figure 1.

Experimental design. Each subject participated in the experiment over the course of two nights. On night 1, subjects saw two light levels (10 lux or 40 lux) of the same light spectra, either blue (B) or red (R) following a dark (D) condition; subjects experienced the other light spectra at both light levels on night 2. Note: Subjects 12 and 13 did not complete the experiment, so their data are not presented here.