By Dr. Liji Thomas, MD Reviewed by Lauren Hardaker Apr 13 2026 Data from millions of people reveal that everyday habits, like how much you move, sit, and sleep, could play a crucial role in shaping long-term brain health and dementia risk.  Study: The Relationships between physical activity, sedentary behaviour, sleep, and dementia: A systematic review and meta-analysis of cohort studies . Image credit: TB studio/Shutterstock.com A large new study in  PLOS One suggests that physical activity,