Figure 5.

Temperature and melatonin z-score curves of morning and evening types averaged with respect to habitual waketime. Symbols as in Figure 4. Data for each subject were first expressed relative to the subject’s mean (= 0) and standard deviation (=1). Average curves were complied with respect to each subject’s habitual waketime, with habitual waketime set to a reference value of 08:00 for all subjects. The average hourly z-score for each individual was first calculated, and those hourly values were then averaged across subjects for each of the two groups.