The daily, weekly, and seasonal cycles of body temperature analyzed at large scale

Abstract

As a check for biases that could be introduced by the use of data from an emergency department, we repeated the study analyses after excluding all temperatures in the fever range (≥38.0°C, ≥100.4°F). The exclusion did not cause bathyphase (hollow points) or orthophase (solid points) to change significantly, though it widened their confidence intervals, especially for orthophase. Bathyphase refers to the time of the minimum value in the diurnal cycle of body temperature. Orthophase refers to the time of the maximum value. Confidence intervals are 95%. The displayed times of night, twilight, and day are the average values that occurred across the years of the study period (total study duration: 30 months). The times of night, twilight, and day shift sharply in middle March and early November because the daylight saving time system is used at the study location (Boston, United States). In the daylight saving time system, clock times are advanced by 1 hour on the second Sunday of March and this change is undone on the first Sunday of November. Consequently, times of sunrise and sunset increase by 1 hour in middle March and decrease by 1 hour in early November.

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