Figure 3.

Average relative (percent) power for alpha frequencies and beta frequencies for each lighting condition. Higher levels of EEG alertness were associated with light than with dark; see text for details. Each pair of panels (A through I) represents the average relative (percent) power for alpha frequencies (α) and beta frequencies (β) obtained for a set of lighting conditions relative to those recorded during the corresponding set of preceding dark conditions. Error bars represent ± standard error of the mean (s.e.m.) for each condition. Asterisks represent significant differences (p < 0.00625). Panel A compares α and β obtained from all lighting conditions compared to α and β from the preceding dark conditions. Panels B and C compare α and β for the two light colors relative to α and β for the preceding dark conditions. Panels D and E compare α and β for the two light levels relative to α and β for the preceding dark conditions. Panels F through I compare α and β for the four combinations of light color and light level relative to α and β for the preceding dark conditions.