24 hr electroencephalographic recordings were conducted in undisturbed mice overexpressing Bmal1 in skeletal muscle (A) or brain (B). No differences in baseline sleep amount were found, however, NREM slow wave activity was significantly reduced in mice overexpressing Bmal1 in skeletal muscle (A). Overexpression of Bmal1 in skeletal muscle also significantly decreased the NREM-recovery response to one (24 hr) day of forced wakefulness by means of a slowly rotating wheel (C, D). It is not unusual for mice to obtain brief amounts of sleep (i.e. micro-sleep) during such an extended regimen of forced wakefulness. This sleep obtained during forced wakefulness was also significantly lower in mice overexpressing Bmal1 (A, ANOVA main effect of genotype F(1, 96)=10.12, p=0.002, main effect of time F(11, 96)=4.1, p<0.001; B, NREM sleep amount t(8)=1.85, p=0.047, NREM recovery sleep t(8)=1.9, p=0.039). NREM slow wave activity (a standard marker of sleep intensity) was consistently lower in Bmal1 muscle-overexpressed mice throughout the 72 hr protocol (D, repeated-measures ANOVA F(1,8)=6.57, p=0.04). In contrast, during forced wakefulness waking slow-wave activity was significantly increased in Bmal1 muscle-overexpressed mice (D, repeated-measures ANOVA main effect of genotype, F(1,8)=5.7, p=0.045). Grey bars indicate forced wakefulness, black bars indicate darkness (active period). Data presented as mean ± s.e.m, n = 16 muscle overexpression, n = 16 littermate controls (muscle), brain overexpression n = 8, littermate controls (brain) n = 11. *p<0.05.