[Photo credit: Bureau of Land Management]
When you don’t get enough sleep you feel tired, lazy and unenthusiastic. But when you have an awesome night’s sleep, you feel happy, energetic, relaxed and ready to take on the world. So why then do up to 80% of working adults suffer to some extent from sleep deprivation? What’s going on inside your brain when you sleep? Why is sleep so important that it hasn’t evolved in any way since the beginning of humankind?
Utilising CSF to remove waste products is ingenious because CSF can access every part of the brain easily.
The human brain is the most complex organ on the planet. It is responsible for maintaining and regulating every part of the body and this is a 24 hour a day job. When your body is asleep and resting, your brain is still active, catching up its filing for the day, ensuring other important organs continue to do their job, and cleaning up from a big day of work.
Every function of the brain is vital for life. No one job is more important than another. There are some jobs however, that scientists are just beginning to learn more about. Some of these jobs occur when you sleep.
What Does The Brain Do While You’re Asleep?
- Flush out metabolic waste products.
In the early stages of sleep, the brain cleans itself. In the body, the circulatory system delivers nutrients and oxygen via the bloodstream to every cell. The lymphatic system then picks up waste products from between the cells and dumps them back into the bloodstream to be removed from the body. The lymphatic system however, is not present in the brain. As the brain is jam-packed full of cells and encased in hard bone, there isn’t enough room to utilise the lymphatic system. In a recent study, Dr Maiken Nedergaard and her colleagues at the University of Rochester Medical Centre, discovered that cerebral spinal fluid (CSF) moves through the brain, utilising glial cells to remove waste products, in a similar way the lymphatic system does throughout the rest of the body. Waste products from the brain make their way into the CSF and get transferred into the bloodstream. Utilising CSF to remove waste products is ingenious because CSF can access every part of the brain easily. Dr Nedergaard and her team also discovered that interstitial space swells during sleep. During waking hours, CSF is found mostly around the outside of the brain. However, during sleep, CSF is found to flow freely throughout the brain. This intriguing finding that CSF is responsible for the removal of metabolites, and that it spreads all throughout the brain during sleep, demonstrates how important sleep actually is. A build up of waste products such as Beta-amyloid protein can lead to diseases such as Alzheimer’s.
- Prune old brain cells.
Also in the early stages of sleep, the brain undergoes maintenance. The brain is constantly creating new nerve cells (neurons). From early fetal life, the brain creates many more neurons than it needs in a haste of development. It doesn’t care what the neurons are used for, it just makes them. Over time, the brain prunes old cells that haven’t been used in order to optimise space for more frequently used ones. During sleep, the brain weakens these connections between these neurons, conserving energy, and helping to restore, strengthen and maintain connections between neurons. New research by Vladyslav Vyazovskiy at the University of Surrey, shows that neurons cannot rest and repair themselves independently. They must shut down in areas so as to not disturb each other.
- File information.
The brain begins to file information in the next stage of sleep. The brain processes all the information you’ve taken in throughout the day and organises it into schematic areas. This is how you learn, create memories, and store information. The brain creates new connections between neurons, strengthens existing connections, and weakens unused connections. The brain strengthens often-used connections by sending persistent, high-frequency signals between relevant neurons. The connections weaken when there is very low-frequency stimulation between neurone.
- Make creative connections.
When the brain is filing information during later phases of sleep, it does a really interesting thing - it gets creative. The brain starts playing around and creates new and creative connections. It does this by making connections across areas that would not normally connect with one another. This is possible because the frontal lobe, the area of the brain responsible for logical thought, is switched off during sleep. It allows you to come up with new and creative ideas, or solve that pestering problem.
The brain is the most complex organ this planet has ever seen. Proper sleep is a necessity in order to keep the brain functioning properly. Sleep allows the brain to strengthen and weaken neural connections, learn new things, store memories, and create new ideas. Probably the most important function of sleep is to allow the brain to clean itself.
What solutions or epiphanies have you had following a proper night’s sleep?
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