How did you sleep last night?

Chronic insomnia affects 5 to 10 percent of older adults and is more than just exhausting. Inadequate sleep – of less than 6 hours a night – is linked to an array of illnesses including hypertension, Type 2 diabetes, heart attack, depression, anxiety and premature death. Chronic insomnia also impairs cognitive performance that increases the risk of dementia, especially Alzheimer’s.

In a nutshell, sleeping well, like regular housekeeping, keeps things clean and tidy for the optimal functioning of the body, which in turn reduces the risk of chronic illnesses. This bland statement, however, hardly do justice to the amazing things that go on inside the brain while we’re asleep.

Maiken Nedegaard (above) of the University of Rochester has been studying the neural activity of mice during waking and sleeping hours. Her research suggests that when we are awake, our neurons are packed tightly together, but when we are asleep, some brain cells deflate by 60 percent, widening the spaces between them. These intercellular spaces are dumping grounds for the cells’ metabolic waste – notably a substance called amyloid-beta, which disrupts communication between neurons and is closely linked to Alzheimer’s. Only during sleep can spinal fluid slosh like detergent through these wider hallways of our brain, washing away amyloid-beta and other disease-causing waste materials that the brain produces during our waking hours.

As a bonus, while all this housekeeping and repair occurs, our muscles are fully relaxed as our mental activity are reduced to a minimum. That is why we feel refreshed after a good night’s sleep and exhausted when we don’t get enough of it.

In Greek mythology, the gods Hypnos (sleep) and Thanatos (death) are twin brothers. The Greeks may have been right.

Video
For more on the sleeping brain, view this TED Talk video. Jeff Lliff, a neuroscientist, explores the ingenious ways our brains are designed to clear cellular waste.