Fig. 1

The effect of voluntary wheel running on wakefulness and sleep. a Photograph of a mouse home cage, fitted with a running wheel. EEG recordings were acquired continuously in the freely moving animals while in the home cage. b Top: outline of the experiment. In both experimental conditions, animals were first kept awake by providing novel objects for the last 3 h of the light period (ZT9–12). Subsequently, between ZT12–15, mice had access to running wheels (RW condition) or were kept awake by providing novel objects without running wheel access (EW condition). EEG recordings were acquired and analysed over the entire 24-h period between ZT0–24 in either condition. Bottom: time course of RW activity during the experiment, shown in 5-min bins. Note that the first 3 h of the dark period (ZT12–15) is dominated by spontaneous wheel running in the RW condition only. c Hypnogram of a representative mouse during the two experimental conditions, RW (top) and EW (bottom). The plots depict colour-coded EEG slow-wave activity (wakefulness: green, NREM: blue, REM sleep: red) with a 4-s epoch resolution, shown as % of the mean SWA over the 24-h period. d Wake EEG spectra during the wheel running ‘RW’ and the exploratory wakefulness ‘EW’ condition. Mean values, SEM. Horizontal bars depict frequency bins where differences between the RW and EW spectra were statistically significant (p < 0.05). e Relative wake EEG spectra during the exploratory wakefulness (ZT12–15) for frontal and occipital EEG derivations, expressed as percentage of EEG power during wake between ZT9–12 (100%). Significant differences from ZT9–12 are shown as horizontal lines (top: frontal, bottom: occipital). f Latency to the first consolidated sleep episode > 1 min (RW, 109.6 ± 42.6; EW, 62.9 ± 30.1 min, p = 0.04, Wilcoxon rank sum test). The dots indicate individual mice, black line connects dots signifying average values across animals