What is the link between sleep and Alzheimer’s?
A good night sleep is invigorating and rejuvenates the body and the mind. But when we sleep badly we feel sluggish and less energetic.
Poor sleep can have a disrupting effect on our health over the long term. Scientists have now discovered that just one night of poor sleep has an even more disturbing effect – it can cause an increase in amyloid beta which is a protein associated with Alzheimer’s disease.
In fact a week of poor restless sleep leads to the increase in tau – another brain protein which is linked to brain damage in Alzheimer’s disease and other neurological diseases.
This study recruited 17 participants, aged 35 to 65 with no sleep problems of cognitive impairments to understand how poor sleep damages the brain.
The researchers compared each participant’s levels of amyloid beta and tau after the disrupted sleep to the levels after uninterrupted sleep and found that there was a 10 per cent increase in amyloid beta after a single night of interrupted sleep.
Each participant wore an activity monitor for about 2 weeks to measure how much sleep they had every night.
After five or more night, participants were asked to spend a night in a specially designed sleep room at the School of Sleep. The room is dark, soundproof, has climate control and is conducive for sleeping. It houses one person at a time.
Participants wore headphones and were attached to electrodes to monitor their brain waves.
They were randomly assigned to have their sleep disrupted during the night they slept in the special room.
Every time the participants entered deep dreamless sleep which is characterised by slow-wave brain patterns, the researchers sent a series of beeps through the headphones, which would gradually get louder, until the participant’s slow wave patterns dissipated and they entered shallower sleep.
The participants who had disturbed sleep reported feeling tired and unrefreshed the next morning, although they slept just as long as usual and rarely remembered being awoken at night.
The participants also underwent a spinal tap to measure the levels of amyloid beta and tau in the fluid surrounding the brain and spinal cord.
A month or more later, the process was repeated again but those who had their sleep disturbed were allowed to sleep undisturbed while the others had their sleep disturbed by the beeps.
The researchers compared each participant’s levels of amyloid beta and tau after the disrupted sleep to the levels after uninterrupted sleep and found that there was a ten per cent increase in amyloid beta after a single night of interrupted sleep. There was now corresponding increase in tau levels.
But participants whose sleep monitors showed that they had restless sleep at Home one week before the spinal tap showed significant increase in tau levels.
The researchers believe that a single night or even a week of restless sleep will not have much effect on the risk of developing Alzheimer’s disease, as the amyloid and tau levels will probably go down the next time a person sleep well, but it is of concern in people who suffer from sleep apnoea and in those who have chronic sleep problems.
The brains of people who have Alzheimer’s disease is dotted with amyloid beta plaques tangled with tau protein which causes the brain tissues to atrophy and die.
Chronic sleep problems especially during middle age, can increase the levels of these brain proteins – which animals studies have shown that it leads to an increased risk of Alzheimer’s.
While the researchers don’t know if sleeping better or more sleep can reduce the risk of Alzheimer’s, getting a good night sleep can never hurt and will only leave you feeling better the next morning, amongst other benefits.
Source: Brain
