One bad night raises brain levels of Alzheimer's molecule, research shows
Just one night of poor sleep can significantly increase levels of a toxic brain substance linked to Alzheimer's disease, a study has found.
Researchers used a radioactive tracer to measure the build-up of amyloid-beta peptide in the brains of 20 volunteers aged 22 to 72 over the course of two nights.
For one of the nights, participants were allowed a restful period of sleep. For the other, they were sleep deprived.
Positron Emission Tomography (Pet) scans were used to track the tracer. They showed that restricting sleep to as little as five hours led to a "significant increase" in amyloid-beta burden in two brain regions vulnerable to damage in Alzheimer's patients.
The hippocampus plays a key role in memory while the thalamus acts as a relay centre for motor and sensory nerve signals.
Amyloid-beta is a protein building block that accumulates in sticky "plaques" in the brains of people with Alzheimer's, leading to the destruction of neurons.
Sleep may play an important role in a natural "waste disposal" system that clears potentially harmful material including amyloid-beta out of the brain, scientists believe.
The new findings are published in the journal Proceedings of the National Academy of Sciences.
US lead author Dr Ehsan Shokri-Kojori, from the National Institutes of Health in Bethesda, Maryland, and colleagues wrote: "This study documents an effect of one-night sleep deprivation on amyloid-beta burden in the hippocampus, thus providing preliminary evidence that sleep, among other factors, could influence amyloid-beta clearance in the human brain.
"Our results highlight the relevance of good sleep hygiene for proper brain function and as a potential target for prevention of Alzheimer's disease."
Dr David Reynolds, chief scientific officer at the charity at Alzheimer's Research UK, said: "There is growing evidence of a link between disrupted sleep and Alzheimer's disease, but it is difficult to tease apart cause and effect to determine whether sleep problems might cause Alzheimer's brain changes or vice-versa.
"This very small study suggests that one night of sleep deprivation can raise levels of the hallmark Alzheimer's protein amyloid, strengthening suggestions that sleep is important for limiting the build-up of this protein in the brain."