Figure 1

Comparison of bedtime and wake time (mean + SD) among TT (n = 223), TC (n = 91) and CC (n = 14) subjects during weekdays (white bars) and weekends (black bars). During weekdays, both the bedtime and wake time of CC subjects were significantly later than those of TT and TC subjects. During weekends, the results for bedtime were consistent with those during weekdays, but there were no significant differences among genotype groups in wake time. *P < 0.05, **P < 0.01.