It’s always a great relief to get into bed at the end of a long day.
But the exact reason why humans need sleep remains a mystery, according to new research.
It has long been thought that the brain uses sleep to eliminate toxins and get rid of harmful molecules.
However, a new study now suggests the opposite may be true and experts say being active could be more beneficial for “cleansing” the brain.
A team at Imperial College London’s Dementia Research Institute in the United Kingdom used a fluorescent dye to study the brains of mice, tracking how quickly the dye moved from one area of the brain to another before eventually being removed. .
The exact reason why humans need sleep remains a mystery, according to new research (file image)
They found that fluid clearance and movement were markedly reduced during sleep and under anesthesia.
The analysis revealed that dye clearance was reduced by about 30 percent in sleeping mice and 50 percent in mice that were under anesthesia compared to mice that were kept awake.
Although the findings have yet to be confirmed in humans, they cast doubt on the long-held belief that sleep eliminates toxins through the glymphatic system, a mechanism that removes waste from the brain.
Previous research has suggested that sleep is important in preventing dementia, as it is during this time that toxic proteins are removed from the brain.
Study co-senior author Nick Franks, professor of biophysics and anesthetics at Imperial College London, said: “The field has been so focused on the idea of elimination as one of the key reasons we sleep and of course , we were very surprised to see the opposite in our results.’
The researchers also said that the size of the molecules can affect how quickly certain toxins move through the brain and that some compounds are eliminated through different systems.
“So far, we don’t know what it is about these states that slows down the removal of molecules from the brain,” Professor Franks added.
“The next step of our investigation will be to try to understand why this is happening.”
Study co-leader Professor Bill Wisden, acting director of the UKDRI, said: “There are many theories about why we sleep, and although we have shown that the elimination of toxins may not be a key reason, it cannot be argued that sleep is important.
«Sleep disturbance is a common symptom experienced by people living with dementia; However, we still do not know if this is a consequence or a determining factor in the progression of the disease.
“It is very possible that sleeping well helps reduce the risk of dementia for reasons other than eliminating toxins.
«The other side of our study is that we have shown that brain clearance is very effective during the waking state.
“In general, being awake, active, and exercising can more effectively cleanse the brain of toxins.”
The findings were published in the journal Nature Neuroscience.
