Proper hours of sleep are crucial for the human body as it helps with physical renewal, hormonal regulation, growth, metabolism, etc. In addition to these myriads of benefits derived from sleep, a new study has shown that deep sleep also clears out the wastes in the human brain which is critical for cognitive health.
The study published in the journal 'Science Advances' and led by Dr. Ravi Allada from Northwestern University found that deep sleep possesses an ancient and restorative power to clear waste from the brain. The waste potentially has toxic proteins that could lead to neurodegenerative diseases which make its clearance from the body an essential process.
"Waste clearance could be important, in general, for maintaining brain health or for preventing neurogenerative disease. Waste clearance may occur during wake and sleep but is substantially enhanced during deep sleep," said Dr. Ravi.
The study was conducted on the brain activity and behavior in fruit flies whose neurons that govern their sleep-wake cycle are strikingly similar to that of human beings. The researchers investigated the proboscis extension sleep (PES) stage in fruit flies that is similar to the deep sleep stage in humans. The fruit flies were found to retract their proboscis or snout many times during this stage. According to the researchers, this motion possibly moves the fluids to the fly version of kidneys thereby facilitating the clearance of waster and recovery of injuries.
The study sheds light on why sleep is essential for the survival of all living organisms. The study also indicates that waste clearance is an evolutionary conserved core function of sleep.