Dementia is a growing problem as the population ages. Sleep disturbances are among the most challenging behavioural problems associated with dementia and are a primary reason for moving family members into institutionalised care. Research, primarily with people institutionalised with severe dementia, suggests that accelerated ageing in the circadian time-keeping system contributes to the increasingly disrupted pattern of daytime sleep and night time awakenings. This project will explore using an intervention to improve the sleep of people with dementia living in the community, and the sleep and quality of life of their family caregivers, using timed light therapy and exercise to enhance the activity of the circadian pacemaker. Sleep of patient/caregiver pairs will be monitored objectively and subjectively before and after the 5-week intervention. If the intervention is successful, a full study will be conducted with a more diverse group of patients, with the intervention administered by community workers from Alzheimers New Zealand.