It is known that salt is important for cognitive function. Although some studies do link a lower level of sodium with a reduction in blood pressure and heart disease, studies have also found that low levels of sodium could impair memory and brain function. Now, a study from researchers at the University of Copenhagen shows that the level of salts in the brain plays a critical role in whether a person is asleep or awake. The team states that their findings could be highly salient to psychiatric diseases such as schizophrenia and convulsive fits from lack of sleep as well as post-anaesthetization confusion.
Previous studies show that salt is an electrolyte which is used with other electrolytes in the body to transmit electrical signals. It is particularly important for transmitting nerve signals throughout the body, including the brain, where salt is used as a stimulant to encourage the brain to make new memories, for instance. The current study shows that the level of salts in the body and brain differ depending on whether the person is asleep or awake, and have successfully influenced the level of salts to control a mouse’s sleep-wake cycle.
The current study utilises mice to test whether injecting salt into the brain enables control of the mouse’s sleep-wake cycle, independently of the so-called neuromodulators, which are compounds which play a decisive role in waking-up every morning. Results show that adrenalin and other neuromodulators change the level of salts surrounding the neurons and the salt balance then decides whether to make the neurons sensitive or not to stimulation. Data findings show that when the person is awake, the salt balance makes neurons highly sensitive to stimulation, as opposed to the salt balance in the brain during sleep, where the level of salts makes it harder to activate the neurons.
The team note that the research conducted used to focus only on the brain’s neural activity as a means of mapping and analysing complicated processes such as being asleep or awake. Results show that the brain uses something as simple as changing the level of salts to control whether the person is asleep or awake. They go on to stress that studying only neurons in order to understand brain activity is not enough and that future studies must include all the supportive cells, especially astrocytes, which regulate the level of salts in the brain.
The team surmise that their findings show that salts play a larger role than previously thought. They go on to add that their discovery reveals a completely new layer of understanding of how the brain functions. For the future, the researchers state that the global medical community must learn more about how sleep is controlled to hopefully raise understanding of why some people suffer convulsive fits when suffering from sleeplessness and insomnia.
Source: University of Copenhagen