Effect of sleep and sleep deprivation on the inter-animal variability of transcript expression in the lung. 210 probes showed statistically significant changes in expression variability as a function of sleep duration. (A): The coefficient of variation (CV) of probe expression among spontaneously sleeping mice after 3, 6, 9, and 12 hours is plotted against the CV of the same probe at baseline (lights-on). The red line of identity (x = y) demarcates no change in inter-animal variability. Probes with statistically significant temporal changes in variance among sleeping mice are colored in red. These probes remain clustered and show systematic changes with variability as sleep progresses. (B): The coefficient of variation of gene expression among mice deprived of sleep for 3, 6, 9 and 12 hours is plotted against the CV of the same gene at baseline. The probes with statistically significant changes in variability among sleeping mice are again colored red and now demonstrate a different temporal progression. (C): The CV of probe expression among spontaneously sleeping mice after 3, 6, 9 and 12 is plotted against the CV of diurnally matched sleep deprived mice. The identified probes remain clustered at all circadian times and show systematic differences in inter-animal variability. Relative to baseline and sleep-deprivation, early sleep enhances inter-animal variability. At the end of the normal sleep period, animals allowed uninterrupted sleep show more uniform expression while sleep-deprived animals become relatively desynchronized. (D) The data from part (C) is re-plotted now highlighting all probes with Gene Ontology annotations related oxidation-reduction (n = 778, colored blue) and wound healing (n = 361, colored green). These large and physiologically important transcript groups show the same pattern and are synchronized after uninterrupted sleep.