An amateur mountain bike athlete known for his recklessness counted three violent falls in the past year. In all of these falls, his head received a violent blow, be it against the ground or a tree. He sees the neurologist days after the last accident; says he is irritable, anxious, and has trouble concentrating. Also sleeps poorly, but has a habit of not falling asleep and considers sleep a waste of time. He came into the office armed with a skull tomography, luckily normal.
However, there is something to be feared. Repeated head injuries can cause dementia in the future. Small intracerebral wounds release clumps of protein inside the skull, causing inflammation and destruction of brain cells, creating more undesirable concentrations and further destruction. Cyclist symptoms are alarming.
Sleepless nights also cause the same concentration of protein. Thus, our intrepid athlete has two risk factors for dementia: his accident history and his inadequate sleep behavior.
The scientific discovery that sheds light on the relationship between sleep and protein globules is relatively new and dates back to 2012. It came about when the gymnastics system was found in rat brains and later inferred to be human. This system is an intracerebral drainage network that removes metabolic debris from the brain and replenishes nutrients. The lines work actively when you sleep and very little when you are awake. Consecutive sleepless nights will shorten the time these pathways function, and therefore there will be an accumulation of toxic waste that could be one of the triggers for brain degeneration that causes dementia.
But even one night of lack of sleep is enough to cause problems with this sensitive drainage device. Neurosurgeon Per Kristian Eide from the University of Oslo and his team have proven this. The researchers injected a marker molecule into the fluid – the fluid that bathes the brain – from volunteers. Then two different groups were formed. Members of one of them did not sleep the following night while the other participants had adequate rest.
The next morning, all participants underwent a cranial magnetic resonance examination, using a special technique that can detect the tracer molecule. What was seen was the persistence of the artifact in the brains of those who had not slept. Surprisingly, after two nights in which none of the volunteers were further sleep deprived, new tests discovered the persistence of the tracer in the brains of those who had not slept that single night. Build-up due to sleep deprivation will not be cleared for the following nights.
This is not the first time that the immediate effects of sleep restrictions have been reported. A cycle of just four hours of sleep for a few consecutive nights raises blood sugar levels to pre-diabetic levels. People who sleep less than five hours in a week produce an inadequate immune response after a flu shot. Young men have a drop in testosterone after just four hours of sleep for four consecutive days, as if they were ten years older. Hospital data collected in Michigan, United States, showed a 24% increase in heart attacks on the day the clocks advanced one hour in response to a government action similar to our daylight saving time.
Our cyclist needs to review his relationship with sleep. Better nights can benefit your health and alertness, with a good impact on your athletic performance and with the potential to reduce your falls.
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Eide, PK; Vinje, V .; Pripp, AH; Mardal, K.-A .; Ringstad, G. Sleep deprivation affects molecular clearance from the human brain. Brain 2021, 144 (3), 863-874. https://doi.org/10.1093/brain/awaa443.
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Daylight Saving Time and Myocardial Infarction Open Heart https://openheart.bmj.com/content/1/1/e000019
Widespread τ and amyloid β pathology many years after a single traumatic human brain injury – PubMed https://pubmed.ncbi.nlm.nih.gov/21714827/.
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