There are few activities more rewarding than sleep. Provided insomnia isn’t an issue, most people look forward to sleeping and don’t particularly enjoy getting up. There’s no question that sleep is a restorative process — if I go to bed grumpy, I can wake up with a spring in my step; if I go to bed sore, I often wake up pain-free; if I go to bed with a headache or a mild sore throat, chances are it’ll be gone by morning. Those 6-8 hours sometimes seem to do magical things (and that’s without considering dreaming), but a recent study in Science magazine reveals important benefits of sleep that we weren’t even aware of.
Researchers found that during sleep, the brain experiences an influx of cerebrospinal fluid that washes away toxins and waste proteins that accumulated during the day. University of Rochester neurosurgery professor Maiken Nedergaard likens the process to a dishwasher. Being able to get rid of toxins while sleeping has a number of benefits, including a possible reduction in one’s risk of developing Alzheimer’s.
Back in the 1970s scientists uncovered a connection between sleep and health — or more accurately, lack of sleep and health problems. Difficulty sleeping has been identified as an early symptom of Parkinson’s disease, and researchers have identified a connection between Parkinson’s and narcolepsy. The association between brain diseases and sleep disorders has been known for a while, but scientists have never really understood the relationship. This study helps shed light on that association, suggesting that the failure of the brain to successfully rid itself of toxins may be a cause of brain disorders.
Nedergaard and his colleagues identified the increase of cerebrospinal fluid and noticed that it was being pumped into and flushed out of the brain much faster than usual when they examined the brains of sleeping mice. The cerebrospinal fluid could move faster and more easily because the brain cells of the mice shrank when they went to sleep, and when the mice awoke, their brain cells resumed their normal size and the amount of fluid circulating slowed down dramatically. “It’s almost like opening and closing a faucet,” says Nedergaard.
Cerebrospinal fluid washes away waste proteins that accumulate between brain cells and which are actually toxic to those cells. Researchers think this might explain not just brain disorders, but also why we tend to feel mentally fuzzy when we don’t sleep well, and why long-term sleep deprivation can lead to death. They believe that the cleansing process takes enough energy that the brain can’t do it while we’re awake and the brain is in charge of so many other functions.
This process has also been seen in baboons, but hasn’t yet been observed in humans. It likely will be, though, especially in conjunction with treatments for dementia and Alzheimer’s. The researchers found that beta amyloid is among the waste proteins flushed out by the brain during sleep, which is significant because beta amyloid forms detectable sticky plaque in the brains of people afflicted by Alzheimer’s. Beta amyloid amounts accumulate during our waking hours, but are usually flushed out during sleep. It’s possible that facilitating the flushing out of beta amyloid could help prevent Alzheimer’s, which will almost certainly be the focus of future studies.
Not only should we all make sure we get our ZZZZZs, but I also think workplaces should institute mandatory nap time to help keep employees sharp and healthy. Not likely, I know, but a girl can dream, right?