Sleep and EEG features in genetic models of Down syndrome.

Down syndrome is characterized by a host of behavioral abnormalities including sleep disturbances. Sleep and EEG was studied at the age of 3 months in two mouse models of the condition, Ts65Dn and Ts1Cje, carrying one extra copy of partially overlapping segments of the mmu chromosome 16 (equivalent to the human chromosome 21). We found that the Ts65Dn mice showed increased waking amounts at the expense of non-REM sleep, increased theta power during sleep and a delayed sleep rebound after sleep deprivation. In contrast, Ts1Cje had limited sleep and EEG abnormalities, showing only a delayed sleep rebound after sleep deprivation and no difference in theta power. We previously found that mice over-expressing the human APPwt transgene, a gene triplicated in Ts65Dn but not Ts1Cje, also show increased wake and theta power during sleep. These results demonstrate abnormalities in sleep and EEG in Ts65Dn mice and underscore a possible correlation between App overexpression and hippocampal theta oscillations.