Figure 1

Wheel-running behavior is broadly distributed across the 24-h day during gradual exposure to the fragmented day-night cycle (FDN-G) compared to sudden exposure (FDN-S). (A) Schematic demonstrating the difference between the sudden exposure to the FDN cycle (FDN-S) and gradual exposure to the FDN cycle (FDN-G). Comparison between FDN-S and FDN-G occurred during the first 7 days as indicated by yellow shading. (B) Representative actograms of wheel-running activity during 16:8 LD to FDN-S (all FDN-S actograms used for analysis are in the supplementary Fig. S1. This actogram shows extra days for visual comparison with FDN-G over 4 weeks for the main figure only) and (C) 16:8 LD to FDN-G. n = 6 per group. Recording of wheel-running activity commenced as indicated on actograms (mice were in preceding LD cycles as explained in the “Methods” and Supplementary Tables S1). Brackets indicate periods of activity (7 days) used for further analysis. (D) Average of daily (across 7 days) wheel-running activity, collected in 30-min bins, and normalized to the highest daily activity for each mouse for 16:8 LD, FDN-S, and FDN-G. n = 6 per group. (E) Lomb-Scargle, Chi-square, and Wavelet periodograms averaged across 7 days for 16:8 LD, FDN-S, and FDN-G; the average (black line) is plotted with ± SEM error bars. Alignment with the 24-h day indicated by the dotted red line. n = 6 per group, comparison between all groups for Lomb-Scargle: F = 153.3, P < 0.0001***, peak average amplitudes: 1565.57, 473.99, 18.56, Range: 702.93, 189.75, 30.9, and ± SEM: 109.6, 29.5, 6.02 Chi-square: the dashed gray line indicated the significance line (0.05). F = 11.81, P < 0.001***, peak average amplitudes: 305.5, 211.31, 216.0, Range: 75.76, 125.79, 11.94, and ± SEM: 10.4, 17.88, 16.9. Analysis of the daily peaks (Hours 6, 12, 18, 24) for FDN-S and FDN-G. FDN-S: F = 9.58, P < 0.001***, peak average amplitudes: 123.5, 130, 124, 210.7, Range: 113.3, 110.9, 100.9, 125.8, and ± SEM: 12.8, 12.1, 12.6, 15.1. FDN-G: F = 0.19, P < 0.9, peak average amplitudes: 230, 223, 235, 215, Range: 140, 131, 131, 110, and ± SEM: 20, 19.4, 19.4, 17. Wavelet: F = 58.34, P < 0.0001***, peak average amplitudes: 4036.77, 1925.75, 219.59, Range: 2242.45, 1561.01, 280.28, and ± SEM: 350.47, 251.65, 43.14. (F) Average total wheel-running activity across 7 days for 16:8 LD, FDN-S, and FDN-G. n = 6 per group, F = 0.3161, P = 0.7337, ranges: 850.9, 430.4, and 688.3, and ± SEM: 136.67, 83.69, 110.93, n.d. = no significant difference. (G) Percent of total daily activity that occurred during the dark portion(s) for 16:8 LD, FDN-S, and FDN-G. n = 6 per group, F = 53.57, P < 0.0001***, ranges: 10.20, 28.4, 11.29, and ± SEM: 1.83, 2.57, 1.87. (H) Circadian period (tau). The average tau at the peak amplitude of periodograms in “E” is graphed (x-axis) vs. the SEM of the tau for each experimental group (y-axis). The ± SEM error bars for the average tau are also displayed. Alignment with the 24-h day indicated by the dotted red line. n = 6 per group, Lomb-Scargle: F = 15,583.98, P < 0.0001***, peak average tau: 23.95, 25.16, 6, Range: 0.45, 0.95, 0, and ± SEM: 0.06, 0.13, 0. Chi-square: F = 65,535, peak average tau: 24, 24, 18, Range: 0, 0, 0, and ± SEM: 0, 0, 0. Wavelet: F = 0.08, P < 0.922, peak average tau: 24.03, 24.61, 23.46, Range: 0.49, 2.33, 22.16, and ± SEM: 0.07, 0.33, 3.44. (I) Schematic of the Circadian Duration Index (CDI), demonstrating the relationship between the typical duration of mouse wheel-running locomotion and values that would be considered non-circadian and atypical. (J) Assessment of the period of circadian-driven wheel-running activity using the CDI for 16:8 LD, FDN-S, and FDN-G. n = 6 per group, F = 0.40, P < 0.0001***, and ranges: 3.50, 2.50, 2.50 ± SEM: 0.03, 0.01, 0.01.