Salt levels in the brain appear to play a critical role in whether we fall asleep or stay awake, according to a new mouse study by researchers at the University of Copenhagen. The findings are highly relevant to research on psychiatric conditions such as schizophrenia, post-anaesthesia confusion, as well as convulsions or seizures due to sleep deprivation.
For the first time, researchers have shown that the levels of salts in our body and brain differ depending on whether we are asleep or awake. The findings show that by influencing the level of salts, it is possible to control the sleep-wake cycle in mouse models.
“These salts play a much larger and much more decisive role than hitherto imagined. The discovery reveals a completely new layer of understanding of how the brain functions,” says Professor Maiken Nedergaard from the Center for Basic and Translational Neuroscience at the University of Copenhagen.
“First and foremost, we learn more about how sleep is controlled. It may, however, also open up for a better future understanding of why some people suffer convulsive fits when staying awake all through the night.”
For the study, the researchers injected salt into the brains of mice to determine whether the salt levels could affect their sleep-wake cycle. They found that it is the neuromodulators (compounds, such as adrenalin, which play a key role in waking up every morning) that change the level of salts surrounding the neurons. This salt balance then decides whether the neurons are sensitive to stimulation in the shape of a touch.
When we are awake, for example, the salt balance makes neurons highly sensitive to stimulation. In contrast, when we are asleep, the salt balance makes it harder to activate the neurons.
“It’s much simpler than previously believed in brain research. The research conducted used to focus only on the brain’s neural activity as a means of mapping and analyzing complicated processes such as being asleep or awake,” says Nedergaard.
The fact that the brain needs seven to eight hours of sleep to function well on a daily basis reveals that there’s much more we need to understand, says Nedergaard. He adds that it’s time we think of the brain as much more than just a group of neurons acting like a computer.
“Our study shows that the brain uses something as simple as changing the level of salts to control whether we are asleep or awake. This discovery reveals that studying only neurons in order to understand brain activity is not enough.”
The findings are published in the scientific journal SCIENCE.
Source: University of Copenhagen