14/05/2025
Scientists have discovered that norepinephrine, released in rhythmic waves during deep sleep, drives the brain’s glymphatic system, which pumps cerebrospinal fluid to clear toxins. However, sleep aids like zolpidem may disrupt this process, reducing the brain’s cleaning efficiency.
Researchers in Denmark discovered that norepinephrine plays a crucial role in the brain cleaning process, at least in mice. During deep sleep, the brainstem releases waves of norepinephrine roughly every 50 seconds. These waves cause blood vessels in the brain to contract, creating slow, rhythmic pulsations that propel surrounding fluid to carry away waste effectively. The scientists found that norepinephrine waves correlate to variations in brain blood volume, suggesting it triggers a rhythmic pulsation in blood vessels. They then compared the changes in blood volume to brain fluid flow and found that brain fluid flow fluctuates in correspondence to blood volume changes, suggesting that the vessels act as pumps to propel the surrounding brain fluid to flush out waste.
“It’s like turning on the dishwasher before you go to bed and waking up with a clean brain,” says senior author Maiken Nedergaard of the University of Rochester and University of Copenhagen, Denmark.
“You can view norepinephrine as this conductor of an orchestra,” says lead author Natalie Hauglund of the University of Copenhagen and the University of Oxford, UK. “There’s a harmony in the constriction and dilation of the arteries, which then drives the cerebrospinal fluid through the brain to remove the waste products.”
Hauglund then had another question: is all sleep created equal? To find out, the researchers gave mice zolpidem, a common drug to aid sleep. They found that the norepinephrine waves during deep sleep were 50% lower in zolpidem-treated mice than in naturally sleeping mice. Although the zolpidem-treated mice fell asleep faster, fluid transport into the brain dropped by more than 30%. The findings suggest that the sleeping drug may disrupt the norepinephrine-driven waste clearance during sleep.
“More and more people are using sleep medication, and it’s really important to know if that’s healthy sleep,” says Hauglund. “If people aren’t getting the full benefits of sleep, they should be aware of that so they can make informed decisions.”
The team says that the findings likely apply to humans, who also have a glymphatic system, although this needs further testing. Other researchers have observed similar norepinephrine waves, blood flow patterns, and brain fluid flux in humans. Their findings may offer insights into how poor sleep may contribute to neurological disorders like Alzheimer’s disease.
For more on this study, see: https://scitechdaily.com/ambiens-hidden-risk-how-zolpidem-may-damage-your-brains-cleanup-system/