Figure 3.

Analysis of phase difference between midsleep and CRHR

(A) Contour-plot comparison of phase differences between CRHR phase and sleep midpoint over a 2-day period for n = 133,775 estimated phase differences from 927 individuals in the Intern Health Study. When the CRHR is out of phase with sleep, it is likely to be similarly out of phase in 2 days.

(B) Partial autocorrelation function of phase differences; the correlation between phase differences separated by a certain lag in days (red lines) remains statistically significant (outside black dotted lines) out to roughly 1–2 weeks.

(C) Histogram of average phase difference across all subjects (μ = −0.45, σ = 2.25 h) with normal fit (red) for visualization only.

(D) Histogram of average absolute phase difference across all subjects (μ = 3.88, σ = 1.56 h), which includes errors due to uncertainty and shifting sleep schedules, with normal fit (red) for visualization only.