By Lecia Bushak | August 14th, 2019
Frequently napping during the day may be a sign of fatigue or growing older, but a new study suggests it may also be a warning sign of Alzheimer’s disease. The study, out of UC San Francisco, found that sleeping too much during the day — especially if there are no sleeping problems at night — could be a sign that the beginning of Alzheimer’s may be impacting the part of the brain associated with staying awake.
The study found that tau protein tangles may be responsible for impacting these brain regions associated with wakefulness and contributing to degeneration, rather than amyloid protein, which was previously assumed.
“Our work showed definitive evidence that the brain areas promoting wakefulness degenerate due to accumulation of tau — not amyloid protein — from the very earliest stages of the disease,” Dr. Lea Grinberg, senior author of the study, said in a press release.
Tau Accumulation in the Brain’s ‘Wakefulness Center’
The study examined the brains of 13 deceased Alzheimer’s patients, as well as the brains of seven healthy controls. The researchers analyzed the brain regions that were responsible for wakefulness, including the locus coeruleus, lateral hypothalamic area and tuberomammillary nucleus. The same brain regions are also associated with narcolepsy, a disorder involving excessive sleepiness during the day.
The researchers found a good deal of tau protein buildup in all of these wakefulness brain regions, with some losing up to 75 percent of their neurons.
“It’s remarkable because it’s not just a single brain nucleus that’s degenerating, but the whole wakefulness-promoting network,” lead author Jun Oh, a Grinberg lab research associate, said in the press release. “Crucially this means that the brain has no way to compensate because all of these functionally related cell types are being destroyed at the same time.”
The researchers concluded that there needs to be a greater focus on how tau protein accumulates in brain regions in the earlier stages, rather than amyloid protein, as this may contribute to early stages of Alzheimer’s disease.
Alzheimer’s and Sleep
This isn’t the first study to link disrupted sleeping to Alzheimer’s disease. Past research has shown that excessive daytime napping was associated with Alzheimer’s and a greater build-up of beta-amyloid, a compound that disrupts communication between neurons and destroys them over time. A study published earlier this year also pinpointed an increase in accumulated tau protein in brains of people who experienced less deep sleep.
Disrupted or deprived sleep, as well as poor sleep hygiene, can have a huge effect on your brain. Getting a good night’s sleep is responsible for clearing beta-amyloid; and not getting enough has been linked to an increase in beta-amyloid, according to the National Institutes of Health (NIH). Whether disrupted sleep contributes to Alzheimer’s or Alzheimer’s causes disrupted sleep will have to be the subject of further research.