Sleeping pills could be harming your sleep, new study warns

Sleeping pills may impact the brain’s ability to ‘cleanse’ itself during sleep, new research suggests.

A study, which looked into what happens in mice when the brain sleeps, found that zolpidem (a medication commonly used in sleeping pills) disrupted their ‘brainwashing’ system. Researchers concluded that deep sleep may wash away waste in the brain that builds up during waking hours in a process that is essential for maintaining brain health.

The findings, published in the journal Cell, suggest that using sleeping pills may impact cognitive function in the long run. "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.

"We're essentially asking what drives this process and trying to define restorative sleep based on glymphatic clearance."

The built-in waste removal system in the brain is called the glymphatic system. It circulates a clear liquid in the brain and spinal cord (called cerebrospinal fluid) to clear out waste. The process helps to remove toxic proteins that form sticky plaques, which linked to neurological disorders, such as Alzheimer’s disease.

The team of Danish scientists found that norepinephrine, also called noradrenaline – best known for its roles in the fight-or-flight system – plays a key role in brain ‘cleansing’ in mice.

"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."

But after giving the mice zolpidem, they found the norepinephrine waves during deep sleep were 50 per cent lower than in mice not given sleep aids. The zolpidem-treated mice fell asleep faster, but fluid transport into the brain dropped more than 30 per cent, suggesting that sleeping pills 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."

If these results can be replicated in human studies, their findings may offer insights into how poor sleep may contribute to neurological disorders like Alzheimer's disease.

"Now we know norepinephrine is driving the cleaning of the brain, we may figure out how to get people a long and restorative sleep," says Nedergaard.