In the quest for an animal model of Parkinson's disease that mimics motor and non-motor symptoms of human Parkinson's disease (PD), scientists have developed strains of mice that overexpress alpha-synuclein. By studying a strain of mice bred to overexpress alpha-synuclein via the Thy-1 promoter, scientists have found these mice develop many of the age-related progressive motor symptoms of PD and demonstrate changes in sleep and anxiety.