For Brain Health, It's Important to Sleep on Your Side 0 136

However, several years ago, Maiken Nedergaard and her team at the University of Rochester discovered a unique waste clearance system in the brain. The blood vessels in the brain are surrounded by sheaths formed by the extensions of astrocytes—supporting or glial cells. This creates a double tube, and the 'contaminated' interstitial fluid penetrates between its walls, filtering waste into the blood vessel. Astrocytes create pressure within it, making the filtration active rather than passive. This system has been named the glymphatic system, as it functions similarly to the regular lymphatic system but consists of glial cells.

The efficiency of the waste clearance system depends on the functioning of the membrane channels of astrocytes, which require a significant amount of energy. This led researchers to hypothesize that the brain's glymphatic system is active during sleep: since energy is not spent on the activity of neurons, perception, and analysis of external signals, it can be directed towards waste clearance.

Further experiments confirmed this hypothesis: active pumping of interstitial fluid through the glial filter occurred specifically during sleep. During sleep, the distance between nerve cells increased by 60%, allowing for the expansion of channels for the circulation of cerebrospinal fluid and facilitating its access to the glymphatic system. In controlling this system, researchers identified the neurotransmitter norepinephrine, the level of which significantly decreases during sleep and increases upon waking.

If the glymphatic system is activated during sleep, does that mean its function depends on the position in which we sleep? Indeed, as Maiken Nedergaard and her colleagues from the University of Rochester, along with researchers from Stony Brook University, discovered, body position during sleep affects the efficiency of waste clearance processes in the brain. The experiment was conducted on animals: laboratory rodents were injected with a special marker to track how effectively damaged proteins were cleared from the brain, and they were placed to sleep. As reported by the authors of the study in the Journal of Neuroscience, the brain's 'drainage' worked most effectively when the animals slept on their sides. It is worth noting that both animals and humans most often sleep in this position, which may be related to the functioning of glymphatic channels (although the results obtained require confirmation in studies involving humans).

The experiments tracked damaged molecules such as tau proteins and beta-amyloid, which accumulate in neurons and can cause Alzheimer's syndrome. It is known that many neurological diseases, including neurodegenerative syndromes, are associated with sleep disorders. Perhaps a malfunction in the waste clearance system, activated during sleep, contributes to the development of such diseases. Thus, proper sleep not only restores mental functions but also effectively cleanses the brain of harmful substances.