Finding people at higher risk earlier could allow doctors to recommend lifestyle changes, monitor brain health more closely, and prepare future treatments before major damage occurs. Instead of relying on memory tests or brain scans, the system studies brain activity while people are asleep. During sleep, the brain produces many different electrical patterns, and researchers believe these patterns contain valuable information about brain health. The new machine-learning model estimates a person’s brain age rather than simply looking at their actual birthday. Delta waves are linked with deep, restorative sleep, while sleep spindles are believed to help the brain organize and store memories.