Weaker, fragmented body clocks are linked to higher dementia risk, new research suggests.
The study also found that people whose activity levels peaked later in the day, rather than earlier, faced a higher risk.
Circadian rhythm is the body’s internal clock, regulating the 24-hour sleep-wake cycle and other processes including hormones, digestion and body temperature.
With a strong rhythm, the body clock aligns well with the 24-hour day, sending clear signals for body functions.
Researchers at UT Southwestern Medical Center in Texas studied 2,183 people with an average age of 79 who did not have dementia.
Participants wore small heart monitors for an average of 12 days to measure rest and activity patterns.
Over an average follow-up of three years, 176 people developed dementia. Those with weaker rhythms had nearly 2.5 times the risk of dementia compared to those with the strongest rhythms.
People whose activity peaked at 2.15pm or later had a 45 per cent increased risk compared to those peaking earlier in the afternoon.
Wendy Wang, the study author, said: “Changes in circadian rhythms happen with ageing, and evidence suggests that circadian rhythm disturbances may be a risk factor for neurodegenerative diseases like dementia.
“Disruptions in circadian rhythms may alter body processes like inflammation, and may interfere with sleep, possibly increasing amyloid plaques linked to dementia, or reducing amyloid clearance from the brain.
“Future studies should examine the potential role of circadian rhythm interventions, such as light therapy or lifestyle changes, to determine if they may help lower a person’s risk of dementia.”
