Sleep deficit may lead to dementia, per 25 year study

Middle-aged adults who get less than six hours of sleep face an increased risk for dementia, compared to those who regularly snooze for seven hours, according to a large-scale British study spanning 25 years, per an article in TheNewYorkTimes.

The results suggested persistent short sleep cycles among adults aged 50, 60, and 70 were linked to a 30% greater risk of dementia. The study took into account factors like mental health, socio-demographics and cardio-metabolic state.

“Persistent short sleep duration was associated with an increased risk of dementia compared to those with persistent normal sleep duration,” study authors wrote.

A team of French researchers published findings in the Nature Communications journal on Tuesday, stemming from a Whitehall II study involving nearly 8,000 British participants.

Dementia is a broad term for neurodegenerative disease affecting memory, attention and communication, according to the Centers for Disease Control and Prevention, which estimates 5 million adults aged 65 and over were living with dementia in 2014. The agency projects this figure will more than double to nearly 14 million by 2060.

The risks for dementia significantly increase with older age, especially among those 65 and older, the CDC says, though other risk factors include family history and race/ethnicity.

To reach their conclusions, researchers ran repeat measurements on 7,959 participants’ sleep duration over a course of 25 years, collecting self-reported data but also information from wristwatch accelerometers, and 521 participants went on to develop the disease.

Evidence has suggested sleep supports cognitive performance and clears toxic beta-amyloid protein plaques from the brain, thus sleep deprivation can result in “a detrimental effect,” study authors noted. Amyloid plaques can disrupt nerve cells in the brain in Alzheimer’s disease, said to account for the vast majority of dementia cases.

“Amyloid plaque build-up contributes to poor sleep in older adults through its direct impact on sleep-wake regulator brain regions,” authors wrote.

Noteworthy: Difficulty sleeping is sometimes an early sign of dementia, as noted in a corresponding study done at the University of Paris, but does not specifically link sleep duration and dementia risk.

Personally, I find a Power Nap (20-30 mins) to be extremely beneficial and refreshing, but I could not find an association with napping adding to a persons cumulative sleep time.