Scientists have spent years trying to figure out the purpose of sleep. There are a few theories, but one of the more popular explanations among scientists is that sleep serves as a means to clear metabolic wastes that accumulate in the brain while we are awake (Xie et al., 2013). While our bodies are in a state of wakefulness, the brain is busy receiving information from the body, interpreting the information, and guiding the body’s response to those signals. Unfortunately, many of these processes involve reactions which produce waste products and proteins that are toxic to brain cells. Getting rid of these wastes requires a large amount of energy by the body. It is not possible for the brain to both cleanse itself and carry out the everyday functions and tasks of the brain. That is one of the reasons why sleep is so important to the biological function and well-being of animals and humans.
In a study published in Neurology, Gelber et al. (2015) showed how sleep deprivation causes direct damage to the brain. Subjects who spent less time in slow-wave sleep (SWS) or deep sleep had greater levels of cerebral microinfarcts (cellular death of the brain). Over time, these microinfarcts start to accumulate and may cause significant lasting damage to important cognitive networks and account for neurologic disfunctioning. However, the results of this study seems to suggest that having higher levels of SWS may protect against cognitive decline.
In addition, scientists from Washington University showed findings that sleep deprivation is associated with proteins known to be connected with Alzheimer’s disease (Lu et al., 2017). With so much build up and damage to the brain that disruptions in sleep may cause, it is no surprise that Alzheimer’s and other diseases associated with dementia are linked to sleep disorders and people who suffer from consistently poor sleep.
Recent research has also shown that even more than interfering with the brain’s ability to clean itself, sleep deprivation may actually cause toxic substances to be imported into the brain. According to a study done by researchers at the Mexican Metropolitan Autonomous University, sleep loss may lead to a degradation of the brain-blood barrier and allow some unwanted substances to cross this barrier which could harm cells and tissues of the brain (Hurtado-Alvarado et al., 2016). The blood-brain barrier is a highly selective semi-permeable membrane which helps protect the brain from potentially dangerous toxins and foreign substances. As a result, any break down of this barrier can prove to be potentially dangerous or even lethal for humans.
While further studies and research is still needed to fully understand the underlying mechanism behind neurotoxins and sleep, the results seem to indicate that sufficient sleep is important in protecting the brain. Anyone who has had sleepless nights knows the uncomfortable feeling they experience the next day. The science shows that these sleepless nights eventually add up in a very negative way. So, the next time you are worrying about whether to sleep or spend extra time playing or doing work, do yourself a favor and get a good night’s sleep.
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