Science is waking up to how sleep affects our brain

Sleep: We know we need it, and it’s bad if we don’t have it.

Beyond that, there isn’t enough research to explain exactly why that is true. But it is true, said Nancy Stewart, D.O., assistant professor of pulmonary, critical care and sleep medicine at the University of Kansas School of Medicine. And despite having only about 50 years of sleep research to work with, she added, there is enough evidence that what we do during sleeping hours will determine how well our other organs can do their jobs. Especially our brains.

“Sleep research is in its infancy,” she said. “As a civilization, we started learning about the heart more than 200 years ago. It was only last year that the American College of Cardiology and the American Heart Association decided to prioritize sleep and list it as one of the top eight most important things for heart health.”

Stewart explained that the brain does three critical things during sleep. “It cleanses the toxins from your body that build up in the cerebral spinal fluid,” she said. “It stores memories and packages them in the correct places … and it also creates and restores hormones.”

We know that the brain goes through four cycles of sleep. The fourth and deepest cycle is commonly referred to as REM (Rapid Eye Movement) sleep.

“REM is active sleep … when your brain is dreaming but you are paralyzed,” Stewart said. “Our brain has chemicals that cause muscle paralysis.” Any disruption of this cycle means there is less time for the brain to complete its mission, possibly causing damage to other organs.

Serious sleep issues include REM behavioral disorder, when the brain isn’t able to paralyze the muscles, and a person acts out their dreams through physical movement — disrupting the duration and quality of sleep.

Other issues include insomnia, difficulty falling or staying asleep and restless legs syndrome, which is the urge to move rather than relax. “Another common reason for sleep disruption is apnea, when the upper airways (above the vocal cords, and at the back of the throat) close or narrow too many times per hour and breathing temporarily stops,” Stewart explained.

Apnea can be quite serious when breathing temporarily stops and oxygen levels in the body drop. However, apnea is treatable through various methods like using a CPAP (continuous positive airway pressure) machine that creates pressure to open the airway or different surgical options. “It is believed that globally there are more than a billion people with apnea, and 90% of them don’t know they have it,” said Stewart.

Too many sleep disruptions mean the brain doesn’t have enough time to complete its three main tasks. “The brain is like Grand Central Station at night,” Stewart said. If left untreated, sleep issues can cause high or low blood pressure, cognition issues, dementia or even stroke. In other words, lack of sleep can cause your body to wear out before its time.

So, what else do researchers need to learn about sleep? “Everything!” Stewart said with a laugh. There is a lot of research being done now — and much more on the horizon, she added. But in the meantime, she said people should use the screening tools we have now to prevent diseases that begin with sleep and brain health.

Begin by talking to your primary care doctor about your sleep habits and asking what screenings you might need. “Doctors typically don’t ask about sleep issues unless you bring it up,” she said. “And since it happens at night, you can’t observe it like you can with a broken leg; it can be difficult to talk about. But we can change that.”