Figures 6a (left) and 6b (right).
Mean ± SD sleep start times at Day 1 and Day 7 during the intervention weeks for each group (normal sleepers and early awakening insomniacs) and for both light conditions (flashing red and flashing blue). Sleep start times after flashing blue light at Day 7 were significantly later than at Day 1 in both, normal sleepers (t(13) = 2.1; p = 0.05) and early awakening insomniacs (t(7) = 2.8; p = 0.027). There were no significant differences (p > 0.05) between sleep start times at Day 7 and Day 1 after the flashing red light week for either group. * = statistically significant