Increasing evidence suggests a relationship between poor sleep and the risk of developing Alzheimer disease. A previous study found an effect of sleep on β-amyloid (Aβ), which is a key protein in Alzheimer disease pathology.

After a night of no sleep, even a healthy brain has higher than normal levels of the protein that forms the signature tangles in Alzheimer’s disease, according to a new study from the Netherlands whose objective was to determine the effect of 1 night of total sleep deprivation on cerebrospinal fluid Aβ42 protein levels in healthy middle-aged men.

The study’s senior author Dr. Jurgen Claassen, from Radboud University Medical Center in Nijmegen and his colleagues point out in JAMA Neurology that studies on mice have found decreases in the amount of amyloid-beta in healthy animals’ brains after a good night’s sleep, that suggests sleep plays a role in cleaning out the protein overnight.

To see if the same is true in people, the researchers recruited from the local population 26 middle-aged men (40-60 years of age)with normal sleep habits to have their protein levels measured before and after sleep, or a lack of it.
Sleep was monitored using continuous polysomnographic recording from 3 pm until 10 am. Cerebrospinal fluid samples were collected using an intrathecal catheter at defined times to compare cerebral Aβ42 concentrations between evening and morning.

The researchers found that the men who got a good night’s sleep had amyloid-beta levels in their spinal fluid about 6 percent lower in the morning than when they had gone to bed. The men who were kept awake all night had no change in their amyloid-beta levels. Sleep deprivation, or prolonged wakefulness, interferes with a physiological morning decrease in Aβ42. Reasearchers hypothesize that chronic sleep deprivation increases cerebral Aβ42 levels, which elevates the risk of Alzheimer disease.

See also
Brain may flush out toxins during sleep (2013-11-05)

For more information
Cerebrospinal Fluid β-Amyloid 42 in Healthy Middle-Aged Men

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