Alertness Proven More Effective Than Sleep for Brain Detox

Recently researchers have been analyzing the benefits of sleep-in mammals. They say that numerous theories exist, including processing the previous day’s memories. One idea that has gained wide acceptance is that during sleep, the body clears the brain of toxins and metabolites. 

A new study published in Nature Neuroscience, which included mice, found that awake time cleans the brain more than when asleep or under anaesthesia. The study observed that 30% less fluorescent dye standing in for toxins and metabolites was cleared from the mice’s brains during sleep compared to when they were awake. When the mice were anaesthetized, 50% less of the dye was cleared.  The rate at which dye moved from the ventricles of the brain to other regions was observed which made it possible to measure how the dye eventually passes out of the brain. 

Humans often experience problems like hand-to-eye coordination, mental sharpness or even severe health issues due to lack of sleep. Researchers within the study discovered a theory about why humans and other mammal’s sleep. For example, the position during sleep suggests that it is crucial for survival due to its vulnerability. If so, then the most plausible mechanisms are those that provide a crucial benefit, some sort of basic housekeeping that cannot occur, or occurs very inefficiently, during waking. Researchers also say that sleep allows the consolidation of memory. 

This study has also analyzed that sleeping and being under anaesthesia produce the same reductions in brain clearance. However, researchers expressed several concerns regarding the study that undermined definitive conclusions. 

Since the study was conducted in mice, how it translates to humans is still unknown. Follow-up studies and confirmation before rejecting the idea that sleep is equivalent to brain clearing need to be done. The study’s authors also chose to use a small-molecule dye and that a larger-molecule dye might have produced a different brain-clearing result.It would be important to also see what happens during natural (non-sleep deprived) sleep and across a full normal 24-hour sleep-wake cycle. 

The fact is that levels of proteins linked to neurodegeneration, such as tau, are produced at higher levels during wakefulness when neuronal activity is high. In animal studies protein levels tend to rise during sleep deprivation but in humans, one sleep interruption disrupts the normal regulation of protein especially myeloid beta and tau proteins which are implicated in Alzheimer’s pathogenesis. 

Researchers suggest that too little sleep, and poor sleep, are associated with a higher risk of neurodegeneration, specifically Alzheimer’s disease. So even though sleep may not facilitate clearance of metabolites from the brain, there are other mechanisms through which sleep has restorative properties that contribute to healthy aging of the brain. 

Data in this study show that the waking state gives improved clearance compared to being asleep or anesthetized but the aspects of waking state are still unclear. Researchers say that exercise can improve clearance further, but a new study needs to be conducted here. Preliminary research suggests that physical activity may help clear metabolites from the brain, but further studies are warranted.