Sleep. We know we need it. But researchers don’t know exactly why it is a staple of optimal health.
A new study published in October 2013 provides more clues. In animals, the brain uses sleep to scrub away toxins that accumulate in its tissues throughout the waking day. This research may help scientists investigate why poor sleep is strongly associated with neurological disorders and dementia, including Alzheimer’s and Parkinson’s disease.
“What we still don’t know is whether neurological and memory problems are caused by poor sleep, or whether poor sleep is a symptom of dementia and other disorders,” says Daniel Kripke, MD, a Scripps Clinic psychiatrist and expert in sleep and sleep disorders.
Dr. Kripke points out that, while sensational media headlines like “A Good Night’s Sleep Could Stave Off Alzheimer’s Disease” may be premature, the newly published study could point to new directions in sleep and brain research.
While there are still many questions about sleep and its relation to our health, researchers are learning more every year. Check out the following seven surprising facts.
1. Sleep deprivation may help with depression.
Brain imaging studies in depressed patients indicate that sleep deprivation has antidepressant effects.
2. Insomnia is incredibly common.
Approximately one-fifth of the American population — 50 to 75 million people — experience insomnia almost every night, while 49 percent report having occasional difficulty falling or staying asleep.
3. Driving while sleepy is just as dangerous as driving while drunk.
The likelihood of having an accident while sleep-deprived matches the likelihood of driving a car at or above the legal blood alcohol limit of .08.
4. Too much sleep may be more dangerous than too little.
In studies that have compared the death rates of short sleepers (6.5 hours per night or less) versus long sleepers (9 hours or more), longer was associated more strongly with mortality.
5. We dream during all phases of sleep, not just REM (rapid-eye movement).
For years, researchers thought dreaming was restricted to just one phase of sleep. Today there is speculation that we dream to some extent in all sleep phases.
6. “Siestas” are widespread and normal.
In cultures from Egypt to Mexico, sleep tends to be broken up into two periods — six hours at night, and two in the late afternoon. No matter where they live, all humans generally get the same amount of sleep, but they get it in different ways that are determined by their culture.
7. Sleep medication is not particularly effective and may be dangerous to your health.
“There isn’t a lot of compelling medical evidence for the use of sleep medications,” says Dr. Kripke. That’s because medicated sleep doesn’t seem to lead to better outcomes, and has even been correlated in several studies to several diseases and premature death.