Many studies have shown that circadian rhythms and sleep have effects on learning and memory in humans and in animals. The work I will tell you about shows that there is an important functional interaction between sleep and circadian systems in memory consolidation. We explore two animal models of learning disability. In one, Siberian hamsters, we can non-invasively induce learning disability with a one-time light treatment, and we can restore their learning ability with a brain lesion. In the other model, Down syndrome model mice, we can show learning disability and eliminate it with a pharmacological treatment, and also by the same brain lesion that restores learning in the hamster model. We explore these experimental models to reveal the functional interaction of the circadian and sleep systems and to discover their significance