The Skinny on Sleep
September 2, 2019
“Taken together, the results of studies looking at the role of sleep in hormonal, immunological and memory functions suggest that if you do not get enough sleep, you could—besides being very tired—wind up sick, overweight, forgetful and very blue,” says Dr. Robert Stickgold, PhD., at the Harvard Medical School and a sleep researcher focusing on the relationship between sleep and learning.
We now know, sleep doesn’t just have a one purpose. Instead, it appears to be needed for a many of our biological processes to work at their best and slow our biological aging—from our immune system, to hormonal balance, our emotional and psychiatric health, our learning and memory, to the clearance of toxins from the brain. At the same time, none of these functions fails completely in the absence of sleep, but years of sleep deprivation will make many of these short-circuit and ruin our health.
Just one night of complete, or even partial, sleep loss can interfere with all kinds of bodily functions, such as hormonal activity and our immune protection against infections. Reduced sleep seems to lead to increased weight gain—a theory now supported by at least fifty studies; studies which point to a fifty percent increase in obesity among those studied getting fewer than six hours of sleep. Research also shows an association between sleep restriction and the development of type 2 diabetes.
Adding to the huge effects restricted sleep has on immune and hormonal function, its greatest impact probably occurs in the brain. It seems that when we are sleep deprived, our brain remembers negative words and experiences twice as much as positive words and experiences. Just another reason to get our zzz’s so that we can see the glass as always at least half-full.
“Indeed, several studies over the past 25 years have now concluded that poor sleep can, under certain circumstances, lead to depression severe enough to be diagnosed as major depression and may contribute to other psychiatric disorders as well.” The link with depression has become clearer and seems to directly connect to sleep apnea, a disorder in which the flow of air into the lungs becomes interrupted during sleep. A 2012 study by the CDC found that folks with sleep apnea—men twice as often, and women 5.2 times more often, are likely to experience major depression than their better-rested neighbors. “Of course, finding a correlation between these two conditions is not the same thing as proving that one causes the other,” Stickgold says.
Presently, researchers suspect that the sleep helps the brain transform our waking experiences into memories. A bushel basket of new science published in the last twenty years reveals that sleep participates in memory processing—it controls what we remember, and how we remember it. Something I found very cool is the research showing that memories can change, or be lost altogether, even after the brain records and consolidates them. One recent study finds that sleep does more than just stabilize memories and keep them from deteriorating over time; it actually improves them!
What Stickgold and others now firmly believe: during different stages of sleep and emotional memories are more favorably enhanced during sleep. Science shows us anything we think is important is selectively retained while we float along in dreamland. The bottom line? Sleep, and not wake time, selectively strengthens memories that our brain decides has value to us.
Dr. Daniel Schacter of Harvard University believes our memory is about the future, not the past; we use prior experience to enhance our future performance. When we talk about sleeping on a problem, we want our brain to take the information that is already stored there and do some kind of calculation, to juxtapose different possibilities, to find the best solution to a problem. Lucky for us, it can!
If all the above information doesn’t convince you to make sleep a priority, research now adds to the list that sleep clears waste products from the brain. When the investigators injected beta-amyloid (the precursor of the amyloid plaques—the cause of Alzheimer’s disease) into mice, they found that it was cleared from the brain during sleep at twice the rate as during awake times.
I’ll bet you had no idea how important getting adequate sleep each night truly is for every facet of our health and our aging process. I sure didn’t before I became a gerontologist, but now, don’t get between me and my eight and a half hours. (Yes, I need extra!) Sleep is a not yet fully understood phenomenon that all living creatures share here on Planet Earth, and sleep may help us sleep deeply, experience healthy aging, and feel vibrant every day.
Until next time…Be Vibrant!