Bad news for people who've made a habit of pulling all-nighters. New findings out of the University of Pennsylvania are the first to show that long-term sleep deprivation can lead to the loss of brain cells — possibly resulting in permanent brain damage.
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The news should come as especially worrisome to those employed in shift work – nurses, firemen, truck drivers, and anyone else whose job requires her to regularly work at odd hours of the night. Prolonged and persistent disruption to the body's normal circadian rhythms has been linked to everything from breast cancer to liver disease and diabetes. Now, researchers led by UPenn neuroscientist Sigrid Veasey claim they've found the first evidence that long-term sleep deprivation can actually result in a loss of brain cells. Their findings appear in the latest issue of the Journal of Neuroscience.
Veasey and her colleagues... put laboratory mice on a wonky sleep schedule that mirrors that of shift workers. They let them snooze, then woke them up for short periods and for long ones. Then the scientists looked at their brains — more specifically, at a bundle of nerve cells they say is associated with alertness and cognitive function, the locus coeruleus.
They found damage and lots of it. "The mice lose 25% of these neurons," Veasey said.
This is how the scientists think it happened. When the mice lost a little sleep, nerve cells reacted by making more of a protein, called sirtuin type 3, to energize and protect them. But when losing sleep became a habit, that reaction shut down. After just a few days of "shift work" sleep, the cells start dying off at an accelerated pace.
In other words: It doesn't sound like the occasional all-nighter is going to have any long term negative effects; rather, it's when we become fixed in the sleep-wake cycle of someone like a shift worker that sleep deprivation seems to exact its neurological toll.
The findings jibe with previous research that has found sleep deprivation to have a negative impact on abilities both cognitive and physiological. Further research on the brains of deceased shift workers will hopefully shed more light on this finding.
Something that remains to be seen is where the tipping point for permanent brain damage sits for various kinds of sleep deprivation. For example: the occasional all-nighter may not be as damaging as the ritualized sleep-loss associated with shift work, but what effect might researchers see in the brain of someone who, in spite of sleeping every night, doesn't get enough sleep? For instance: Previous studies have shown that restricting sleep to six hours per night over the course of two weeks can cause a person to perform as poorly on cognitive tasks as if she had forgone sleep altogether for two nights in a row. Could this dulled performance be rooted in physiological damage to the brain?