How Sleep Cleans the Brain
When your head hits the pillow for a good night’s sleep, a number of changes occur in your body. Your heart rate and breathing slow down, as do your brain waves, and your gray matter takes a nice, refreshing bath.
The cerebrospinal fluid surrounding the brain removes metabolic waste accumulated during the day and passes it through the lymphatic system, leaving your brain fresh and clean when you wake up. This nighttime neural jacuzzi is powered by a series of pulsations: cardiovascular pulses from your heart in your arteries, respiratory pulses in the veins and spinal fluid spaces, and slow vasomotor waves in the blood vessel walls.
Now, for the first time, neuroscientists at the University of Oulu in Finland have developed a way to monitor this fascinating process, detailing the procedure in two separate studies.
Using ultrafast magnetic resonance imaging (MRI), they were able to measure these pulsations in healthy volunteers, directly and non-invasively, by following the movements of water molecules in the cerebrospinal fluid.
Read more: “Dream Engineering Could Help You Solve Problems While You Sleep”
The team found that although respiratory and vasomotor pulses sped up during sleep, heart pulses slowed, which they believe reflects more efficient filtration of water in neural tissue. They also discovered that the brain behaves differently during sleep. When you’re awake, blood flow follows neuronal activity, but during sleep this relationship can be reversed.
“During sleep, vasomotor waves in particular, slow pulsations below 0.1 hertz, begin to locally influence not only the movement of fluids but also the electrical activity of the brain,” Vesa Kiviniemi, author of both studies, said in a statement.
The buildup of waste in the brain has been linked to memory problems and other conditions, and the team says this new research could shed light on what happens when this system weakens with age.
“New measurement methods open up the possibility of monitoring – and potentially treating in the future – age-related changes in brain fluid dynamics,” Kiviniemi said.
Until then, remember to give your brain a nice and relaxing bath with good sleep.
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Main image: Se / Adobe Stock
