Sleeping longer than 8.5 hours a night may be a sign of Alzheimer’s
They then performed statistical and sensitivity analyses to determine any links between sleep duration and blood biomarkers.
Of the cohort, 576 (23.9%) reported short sleep (up to and including 6 hours a night), 1,475 (61.2%) average sleep (6-9 hours), and 359 (14.9%) long sleep (more than 9 hours).
Those reporting longer sleep were older, and were more likely to have depression, use antidepressants and have dementia than average sleepers.
All biomarkers tended to increase with longer sleep duration, but the increase was significant only for p-tau181.
P-tau181 had a J-shaped curve, with short sleepers having more than average sleepers. It then increased steadily with more than 8.5 hours sleep, and increased sharply for people reporting 10 or more hours of sleep.
“While the findings do not prove causation, they add to the evidence that alterations in sleep may be an early clinical sign of underlying neurodegeneration and reinforce the role of considering sleep as part of an overall assessment of brain health,” Allder commented.
The authors suggested that longer sleep duration could be a sign of disturbed sleep, and Allder agreed:
“Sleep duration alone tells us very little about sleep quality. Someone spending nine or ten hours in bed may actually experience fragmented or inefficient sleep, repeatedly waking throughout the night without necessarily being aware of it. We know that deep, restorative sleep plays an important role in clearing waste products, including amyloid proteins, from the brain via the glymphatic system. Fragmented sleep may impair restorative processes,” he told Medical News Today.
“However,” he added, “it is equally possible that early Alzheimer’s pathology itself disrupts the brain regions that regulate normal sleep, meaning disturbed sleep could be both a contributor to, and a consequence of, the disease.”
