Does a sleeping pill really help your brain clean itself during sleep?
Good, regular sleep demonstrably helps your brain remove waste products, but whether a sleeping pill enhances that effect has not yet been proven in people. Make sure you get enough sleep at night, and discuss sleep medications with your doctor if you are concerned about memory or dementia.
Sleep does something concrete to your brain: throughout the night, a network of tiny channels around the blood vessels pumps waste products out. In a small study with 39 participants, this was measured directly in people for the first time. After a normal night of sleep, more Alzheimer-related proteins were detectable in the blood in the morning than after a night without sleep. That sounds contradictory, but it actually means the brain had actively transported those proteins out.
People who chronically sleep too little have a less effective waste-removal system. Harmful proteins accumulate and the brain becomes inflamed more quickly. This appears to contribute to the risk of Alzheimer's and Parkinson's disease, though the evidence that it is a true cause is not yet conclusive. In people with Parkinson's disease, the waste-removal system demonstrably works less well than in healthy people, and this is linked to more severe movement problems. Researchers see a similar pattern in mood disorders, ADHD, and autism.
Now for the sleeping pill. One specific medication has been studied that suppresses the brain's wakefulness system: suvorexant. In animal studies it improved sleep and reduced the amount of harmful proteins in the brain. However, there are no long-term studies in people showing that the same happens in us. The claim that 'a sleeping pill cleans your brain' goes beyond what the research currently shows.
Review authors write that suvorexant causes less daytime drowsiness and fewer cognitive side effects than classic sleeping pills, though that is a qualitative judgement without hard numbers. Always discuss the use of sleep medications with your doctor, especially if you are concerned about your memory or the risk of dementia.
This answer draws on four sources: a study with 39 participants using a crossover design to measure brain waste clearance in people, a review article on suvorexant, many studies combined covering 4,224 Parkinson's patients, and many studies combined covering 24 investigations in psychiatric conditions. The evidence that normal sleep removes waste products is still relatively new in humans and is based on a small study. The evidence for impaired waste clearance in Parkinson's disease is stronger and more consistent. The suvorexant data come almost entirely from animal studies; long-term data in people are lacking.