Extended Data Fig. 4: Measures of locomotor and exploratory activity during sleep deprivation.

a, Comparing EMG levels across conditions shows no significant differences between early and late extended wake, regardless of experiment, suggesting that increases in SPW-ripples during sleep deprivation are not attributable to muscle fatigue. Right, same extended wake data, faceted by experiment type (novelty, n = 12 subjects; locomotion, n = 6 subjects; dual, n = 5 subjects) and showing within-subject changes. b, Hippocampal theta shows a strong, significant increase over the course of extended waking in both novelty and locomotion experiments (the lack of change from early to late dual extended wake should be interpreted with care, since it is a comparison of forced locomotion (early) to novelty (late)). The increase in theta during sleep deprivation is the opposite of what one might expect if muscle fatigue had increased during sleep deprivation. c, Over long timescales theta power on its own may be confounded by broader homeostatic tendencies. Taking the ratio of hippocampal theta to hippocampal delta effectively normalizes theta to account for broader spectral changes. The theta:delta ratio does not change significantly from early to late extended wake in novelty experiments. It shows a slight but significant increase in locomotion experiments, and a slight but significant decrease in dual experiments. Black bars represent significant differences, assessed using general linear hypothesis tests on mixed effects models. All tests were two-sided and corrected for multiple comparisons (see Supplementary Table 1 for p-values and effect sizes, and Supplementary Information for confidence intervals; see Methods for details). In a–c, boxplots show medians and quartiles. Whiskers are drawn to the farthest datapoint within 1.5 IQRs from the nearest hinge. d, Normalizing theta by delta (or overall spectral power) still produces a measure that behaves similarly to theta in most respects and provides information complementary to EMG. The black solid line indicates the presence of a significant linear relationship in the absence of an interaction with experiment type. Linear relationships and 95% confidence intervals are model expectations estimated using a marginal effects method (see Supplementary Table 1 for p-values and effect sizes, and Supplementary Information for confidence intervals; see Methods for details).