Sleep-wake homeostasis is crucial for behavioral performances and memory in the general population and in learning disability populations among them Down syndrome patients. We investigated, in a mouse model of Down syndrome, cortical EEG and sleep-wake architecture under baseline conditions and after a 4 hr sleep deprivation (SD). Young heterozygous transgenic mice (S/+) for the human Cu/Zn superoxide dismutase (hSOD-1) were obtained on FVB/N background. Baseline records for slow wave sleep (SWS) and wake (W) parameters were the same in S/+ and control mice whereas paradoxical sleep (PS) episode number decreased and PS latency increased after light off in S/+ mice. These data correlate well the polysomnographic phenotype of young DS patients.