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By Science
News Staff / Source
“Changes
in sleep patterns are common in persons with Alzheimer’s disease and other
dementias,” said Dr. Séverine Sabia, a researcher at the Université de Paris
and the Department of Epidemiology and Public Health at University College
London, and colleagues.
“These
changes are believed to result from sleep-wake cycle dysregulation due to
pathophysiological processes in dementia, particularly those affecting the
hypothalamus and the brainstem.”
“Besides
sleep disturbance, there is growing interest in the association between sleep
duration and dementia.”
“Observational studies show both short and long sleep duration to be associated with the increased risk of cognitive decline and dementia.”
“Some
studies also report change in sleep duration in older adults to be associated
with the risk of dementia.”
The
researchers used data from 7,959 British adults who are part of the Whitehall
II cohort study.
The
participants self-reported their sleep duration six times between 1985 and 1988
(age range: 35 to 55 years) and 2015 and 2016 (aged 63 to 86) enabling the
authors to gauge sleep duration at ages 50, 60, and 70.
Some
participants also wore watch accelerometers over a full week, to derive an
objective measure of sleep duration.
A
total of 521 participants had developed dementia by the end of the study period
in 2019.
The
scientists found that those who slept six hours or less each night while
middle-aged were significantly more likely to develop dementia later in life,
compared to those who slept seven hours per night.
They
did not find any significant link between sleeping for eight or more hours, and
dementia risk.
They
found that the association was independent of potentially confounding factors
such as mental health, or differences in behavior, sociodemographic status, or
heart health.
“Sleep
problems are known to occur in people with dementia, but it remains unclear
whether sleep duration in midlife affects the risk of developing dementia at
older ages,” Dr. Sabia said.
“By
using a very long follow-up period, we have found that short duration sleep in
midlife, assessed more than 25 years before mean age at dementia onset, is
associated with dementia risk in late life.”
“While
we cannot confirm that not sleeping enough actually increases the risk of
dementia, there are plenty of reasons why a good night’s sleep might be good
for brain health. These findings confirm the importance of sleep hygiene for
health.”
“We
know that sleep is important to our brain health, as it is involved in learning
and memory, waste clearance from the brain, and the ability of our brain cells
to remain healthy,” said Dr. Archana Singh-Manoux, also from the Université de
Paris and University College London.
“A
better understand of how sleep features might shape our risk of dementia is
needed, as this might help researchers develop new ways to reduce the risk of
dementia, or to delay its progression.”
_____
S.
Sabia et al. 2021. Association of sleep duration in middle and old
age with incidence of dementia. Nat Commun 12, 2289; doi:
10.1038/s41467-021-22354-2