New research indicates that sleeping between 7 and 8 hours per night is the optimal duration to minimize dementia risk later in life.
A statistical analysis of nearly 4.5 million individuals, pooling data from 69 previous studies, examined the associations between dementia risk and three controllable factors: physical activity, time spent sitting, and sleep duration.
The findings revealed that both prolonged sitting (over 8 hours daily) and insufficient physical activity (under 150 minutes weekly) were significantly linked to an increased chance of developing dementia.
Prolonged sitting, too much or too little sleep, and inactivity were all implicated in dementia risk. (Jacobs Stock Photography Ltd/DigitalVision/Getty Images)
Researchers noted that less than 7 hours of sleep per night correlated with an 18 percent increase in dementia risk, while more than 8 hours was linked to a 28 percent increase. This suggests that both excessive and insufficient sleep can be detrimental.
While the review highlights associations rather than direct cause and effect, experts emphasize that a healthy lifestyle profile, including regular movement, adequate sleep, and reduced sedentary time, may support brain health and potentially delay dementia onset.
The researchers analyzed data from previous studies, including ones connecting a lack of sleep to dementia risk. (Oye-Somefun et al., PLOS One, 2026)
Addressing lifestyle risk factors is seen as crucial, as experts estimate that up to half of dementia cases could be avoided. Future studies are planned to further investigate the interplay between these behaviors over time.