Experts at the American Academy of Neurology recently published a paper that suggested waking up regularly throughout the night, and otherwise having an unpredictable sleep schedule, may be linked to later dementia development.
The paper, published in the online journal Neurology, was called “Association of the Sleep Regularity Index With Incident Dementia and Brain Volume.”
“The aim of this study was to assess the association between sleep regularity, that is, the day-to-day consistency in sleep-wake patterns and the risk of incident dementia and related brain MRI endophenotypes,” the introduction to the paper read.
The study followed 88,094 UK participants for an average of seven years. The mean age of participants was 62.
Participants wore a wristband that measured their sleep. Scientists used this to gauge the probability of a person being asleep or awake at two time points in 24 hours.
A person who always fell asleep at the same time and woke up at the same time would have a sleep predictability score of 100; those with a less regular sleep pattern that was harder to predict would have a lower score.
Researchers looked into how this sleep predictability score measured up against participants’ development, or non-development, of dementia.
What did they find?
People in the lowest fifth percentile had a sleep predictability score of 41, while those in the 95th percentile had a sleep score of 71.
Researchers adjusted for age, sex, and genetic disposition to Alzheimer’s before measuring sleep scores against incidents of dementia (480 participants developed the condition over the course of the study).
They found that, even after accounting for these other factors, those with a worse sleep score were 53% more likely to develop dementia than those with a more regular (medium) sleep pattern.
But there was a cut-off point ― people who had exceptionally regular sleep schedules didn’t see fewer cases of dementia than those who had medium-regular sleep patterns.
Study author Matthew Paul Pase, PhD of Monash University in Melbourne, Australia, said “Effective sleep health education combined with behavioural therapies can improve irregular sleep patterns.”
“Based on our findings, people with irregular sleep may only need to improve their sleep regularity to average levels, compared to very high levels, to prevent dementia. Future research is needed to confirm our findings,” he added.
And the American Academy of Neurology says “The study does not prove that sleep irregularity causes dementia. It only shows an association.”