Fig. 1: Daily activity varies seasonally according to latitude.
From: Seasonal timing and interindividual differences in shiftwork adaptation
a Step data across the year-long internship is collected through a wrist-wearable device. b Geographic coordinates of study participants, with latitudes varying from 21.3◦N to 48◦N. c Mean daily steps binned by meteorological seasons Spring (n = 1709), Summer (n = 2280), Fall (n = 1841), and Winter (n = 1483) (one-way ANOVA, F(3,7309) = 28.95, p = 1.33 × 10−18, η2 = 1.17 × 10-2; with Tukey’s test, *p < 0.05, ****p < 1 × 10−4). d Daily steps are strongly associated with time awake (linear regression coefficient β1 = 549.42, p = 5.36 × 10−155, adjusted R2 = 8.1 × 10–3). The model is fit to individual data (n = 86,536 across 673 subjects) and plotted in bins for easier visualization. Error bars are standard error of the mean. e Mean daily time awake binned by meteorological seasons Spring (n = 342), Summer (n = 672), Fall (n = 564), and Winter (n = 445) (one-way ANOVA, F(3,2019) = 6.43, p = 2.47 × 10−4, η2 = 9.5 × 10–3; with Tukey’s test, **p < 0.01, ***p < 1 × 10−3). f Mean daily steps during the summer minus mean daily steps during the winter for each participant (n = 1471) plotted against their latitude (linear regression coefficient β1 = 32.3221, p = 6.02 × 10−3, adjusted R2 = 4.5 × 10–3). Error bars are the standard error of the mean.
