By John Salak –
“To sleep, perchance to dream.” Just maybe Shakespeare’s Hamlet was on to something when it comes to the benefits or at least power of snoozing and dreaming.
There have been numerous studies on the need and physical benefits of getting a good night’s sleep. But some scientists have been equally intrigued as to why sleep occurs at all, considering the potential consequences of nodding off and being unconscious and vulnerable for a person or an animal in the wild.
Several recent studies may have started to unravel this mystery by discovering that snoozing isn’t just essential for resting sore bodies. It is also an elixir for the brain, especially when deep or rapid eye movement sleep (REM) is involved.
Researchers at Northwestern University, for example, report that deep sleep apparently helps flush waste for the brain. This “ancient, restorative power” also may help clear toxic proteins from the brain that could lead to neurodegenerative disease, the university reported.
“Waste clearance could be important, in general, for maintaining brain health or for preventing neurogenerative disease,” said Dr. Ravi Allada, senior author of the study. “Waste clearance may occur during wake and sleep but is substantially enhanced during deep sleep.”
Admittedly, Allada’s team based its finding on studies of the sleep patterns of fruit flies. But he warned against dismissing these results simply because these tiny insects and humans don’t seem to have a lot in common. The deep-sleep stage in fruit flies, in fact, is apparently similar to deep, slow-wave sleep in humans, which is why fruit flies are used in many sleep studies.
Regardless, Northwestern’s team discovered that during deep sleep fruit flies repeatedly extend and retract their proboscis (or snouts). “This pumping motion moves fluids possibly to the fly version of the kidneys,” Allada said. “Our study shows that this facilitates waste clearance and aids in injury recovery.”
Allada explained their findings providing more insights as to why animals—especially those in the wild—risk sleeping deeply.
“Our finding that deep sleep serves a role in waste clearance in the fruit fly indicates that waste clearance is an evolutionary conserved core function of sleep,” he concluded. “This suggests that waste clearance may have been a function of sleep in the common ancestor of flies and humans.”
Halfway around the world, scientists at Tokyo’s University of Tsukuba came to a similar conclusion by focusing on the brain refreshing benefits of REM sleep, which is when dreams tend to occur.
Previous research has tried to accurately measure the difference in blood flood in the brain between REM sleep, non-REM sleep and periods of wakefulness. The results were mixed. The Tsukuba team was able to achieve better blood flow measurements as well as gauge the differences in electrical activity in the brain of mice during these different periods and the results were startling. They also underscored the potential benefits of dreams.
“We were surprised by the results,” reported Professor Yu Hayashi. “There was a massive flow of red blood cells through the brain capillaries during REM sleep, but no difference between non-REM sleep and the awake state, showing that REM sleep is a unique state”
Refreshing the brain during this process may not be the only benefit of increased blood flow and better REM sleep. Since deteriorating REM sleep and reduced blood flow are often linked to Alzheimer’s disease, Hayashi speculated that his research may open up new insights on keeping the brain strong and even establishing new treatments for Alzheimer’s disease.
Achieving such a promise would be a dream come true.