New research shows that getting a good night’s sleep clears your mind, by washing away waste that builds up in the brain during waking hours. The findings also suggest that sleeping pills seem to disrupt this “brain-cleaning” system. It was already known that our bodies have a built-in waste removal process called the ‘glymphatic system’. It helps to remove toxic proteins that are linked to neurological disorders, such as Alzheimer’s disease by circulating fluid to clean the brain and spinal cord. This latest research found that a molecule called norepinephrine plays a key role in this cleaning process.

During deep sleep your brainstem releases tiny waves of norepinephrine about once every 50 seconds. This molecule triggers blood vessels to contract, thus generating a slow rhythmic flow of pulsations. That movement stimulates the fluids in the brain to carry away waste. Head of the study Dr. Natalie Hauglund says, “It’s like turning on the dishwasher before you go to bed and waking up with a clean brain.” To better understand how this process works they focused on the relationships between norepinephrine, blood flow and brain fluid during periods of deep sleep. They found that the molecule triggers a rhythmic pulsation in the blood vessels which pumps the surrounding brain fluid to flush out waste. “You can view norepinephrine as the conductor of an orchestra,” explained Dr. Hauglund. “There’s a harmony in the constriction and dilation of the arteries, which then drives the cerebro-spinal fluid through the brain to remove the waste products.”

The next step was to find out if this works for both natural sleep and sleep induced by drugs. It was found that the norepinephrine waves during deep sleep were 50% lower in mice that were treated with a common sleep aid drug. They concluded that sleeping pills disrupt the waste clearance process, and this probably applies to humans because we have the same glymphatic system. “More and more people are using sleep medication, so in order to make informed decisions they should be aware that they might not be getting the full benefits of sleep.”