Time spent asleep and awake under the LD 12��12 and LD 1��1 schedules.

Under both schedules, Opn4?/? mice displayed significantly less NREM sleep (NREMS; and were awake more) than Opn4+/+ mice during the (subjective) 12-h light (L) periods. This resulted in a significantly decreased amplitude of the circadian distribution (LD difference) of NREMS time (and waking) in Opn4?/? mice. Under the LD 1��1 schedule, Opn4?/? mice slept less compared to Opn4+/+ mice during all 12 1-h L pulses of the entire 24-h d. Also under the LD1��1 schedule, the circadian distribution of sleep and waking observed under the LD 12��12 condition is maintained only in Opn4+/+ mice (subjective 12-h L period, ZT0�C12, compared to the. subjective 12-h dark (D) period, ZT12�C24).aIndicates significant genotype differences.bThe difference between (subjective) 12-h D and L periods for each lighting schedule and genotype (pt-test). Values represent means��SEM (LD 12��12 n = 9/genotype; LD 1��1 n = 3 and 4, for Opn4+/+ and Opn4?/?, respectively).