Resetting circadian rhythms can improve sleep quality in people at risk for dementia

Older man sleeping peacefully.

Can improving sleep quality protect older adults from cognitive decline? New research presented today at the Alzheimer’s Association International Conference (AAIC) suggests that improving circadian regulation by “resetting” an individual’s biological clock can improve sleep quality in older adults with mild cognitive impairment.

The study, presented this morning by PhD candidate Ryan Falck in Dr. Teresa Liu-Ambrose’s Aging, Mobility, and Cognitive Neuroscience Lab, showed that a combination of sleep hygiene education, bright light therapy, and regular physical activity improved sleep outcomes in community-dwelling older adults between the ages of 65 and 85 years living with mild cognitive impairment.

“We wanted to know if improving individual circadian regulation in adults at risk for dementia could improve sleep quality,” said Falck. “People with mild cognitive impairment often have issues with circadian alignment, and as a result have poorer sleep quality.”

Research indicates that poor sleep in mid- and late-life may increase the risk for developing dementia. Sleep disruption is a common symptom of mild cognitive impairment, a transition stage between healthy cognitive aging and dementia. Chronic poor sleep can significantly reduce quality of life and put adults with mild cognitive impairment at risk of further cognitive decline.

For Falck, it was important to conduct research into a non-pharmaceutical intervention for sleep, as sleep medications are not a long-term solution for poor sleep quality.

“Sleep changes as we get older,” said Falck, “and we need to find ways to address the problem in a more personalized way.”

The study used Philips goLITE BLU fluorescent blue-light boxes similar to those used for light therapy for people with Seasonal Affective Disorder, exposing participants to two one-hour doses per day at 12-hour intervals in order to mimic dawn and dusk. Use of the lights was individually timed; participants also received personalized physical activity counselling and four general sleep hygiene classes.

Sleep hygiene is a set of regular behaviours and environmental conditions conducive to sleep, such as following a regular bedtime routine, reducing blue-light exposure from television or mobile phone screens in the evening, committing to regular daytime exercise, and limiting caffeine and alcohol in the hours before sleep. Blue light in particular can affect an individual’s ability to fall asleep; Falck and colleagues emphasize that the timing of the light is important, as exposure to blue light can either speed up or slow down a person’s circadian clock. However, light timing and exposure varied by study participant; every person has different needs for promoting optimal sleep quality.

“Our results provide new evidence that a personalized behavioral medicine approach may help realign the biological clock to improve sleep quality in adults with mild cognitive impairment,” Falck told AAIC today. “Our hope is that, by improving sleep quality, we can contribute to preventing further cognitive decline in older adults with mild cognitive impairment. More research is needed to test this possibility.”