The Cost of Staying Up Late: The Surprising Connection Between Unhealthy Sleep and Brain Aging: It May Also Increase the Risk of Dementia

The Karolinska Institute in Sweden analyzed brain MRIs and machine learning data from 27,500 middle-aged and older individuals from the UK Biobank. They found that poorer sleep quality is associated with a "brain age" that exceeds the actual age. Sleep quality was scored based on five factors: morningness/eveningness, sleep duration, difficulty falling asleep and staying asleep, snoring, and excessive daytime sleepiness. For each point decrease in the score, the brain age gap widened by about 0.5 years, with those in the poor sleep group showing brains that appeared approximately one year "older" on average. This is partly explained by low-grade systemic inflammation, accounting for 7-10% of the association. The study notes limitations such as self-reported data and a healthier-than-average sample, and while causality is not confirmed, sleep is highlighted as a modifiable intervention point. Proper sleep habits may also reduce the risk of dementia.