Figure 4.

Effects of filtering short wavelengths (<480 nm) from ambient light during night shifts on subjective and objective measures of alertness. Alertness measures were conducted every 2 h from start to the end of the shift on the first night shift and the middle night shift in a series of three night shifts under baseline (black filled circles and black line) and intervention (blue filled triangles and blue line) conditions and the seventh day shift used as the comparator condition (gray filled squares and gray line). Tests included one-choice reaction task, response inhibition (GO/NO-GO) task, and subjective sleepiness. Data represent mean ± SEM. Data were subjected to two-factor (group × time) mixed-model ANOVA followed by Dunnett’s post hoc analysis using the comparator as the control group.