Khaberni - A recent scientific study revealed that circadian rhythm disorders in the body could be an early warning sign of the risk of dementia in the elderly, highlighting the importance of regular sleep and daily activity in maintaining brain health as one ages.
According to the study, published by the journal Neurology of the American Academy of Neurology at the end of December 2025, elderly individuals who exhibited weakened or disrupted daily activity and rest rhythms were more likely to develop dementia compared to those who maintained a regular daily routine.
The circadian rhythm, also known as the daily cycle, refers to the internal system that regulates the sleep-wake cycle over 24 hours, in addition to its role in controlling hormone secretion, body temperature, and other vital functions. The brain drives this system, primarily influenced by light and darkness.
When the circadian rhythm is strong, the body maintains a consistent pattern of activity and rest, even with changes in seasons or daily routines. However, weakening of this rhythm makes the body more prone to disruption, leading to irregular changes in sleep and energy.
The study included 2,183 individuals with an average age of 79 years, none of whom had dementia at the start of the study. Participants wore small devices to monitor physical activity and rest over approximately 12 days, allowing researchers to accurately analyze circadian rhythms.
During a follow-up period of about three years, 176 participants developed dementia. The results showed that those who recorded the weakest daily rhythms were at about two and a half times greater risk of developing dementia compared to those who had strong and regular rhythms.
The timing of daily activity is an important factor
The risk was not limited to weak rhythms alone but also included the timing of the peak daily activity. It was found that individuals whose activity peaked late in the afternoon were 45% more likely to develop dementia compared to those whose activity peaked earlier in the day.
The researchers suggest that a delay in the peak activity may reflect a misalignment of the circadian rhythm with natural environmental signals, such as light and darkness.
Why does this affect the brain?
The lead researcher of the study, Wendy Wang from the University of Texas Southwestern, said that the disruption of the daily rhythm may affect vital processes inside the brain, such as inflammation and sleep quality, and could contribute to the buildup of amyloid plaques associated with Alzheimer's disease, or limit the brain’s ability to dispose of them.
Although the study does not prove that circadian rhythm disturbances directly cause dementia, it suggests they may be an early detectable indicator. The researchers hope that these findings will pave the way for future preventative interventions, such as light therapy, improving sleep patterns, or lifestyle modifications, to reduce the risk of cognitive decline.
The study published in the journal Neurology, based on data provided by the American Academy of Neurology, is one of the largest research efforts linking the regularity of the daily rhythm with brain health in the elderly.
