The widely held idea that you can pay back a sizeable “sleep debt” with long naps later on seems to be a myth, she said in a study published this week in the Journal of Neuroscience.
Long-term sleep deprivation saps the brain of power even after days of recovery sleep, Veasey said. And that could be a sign of lasting brain injury.
Veasey and her colleagues put laboratory mice to check their theory – lab mice were kept awake to replicate the kind of sleep loss common in modern life, through night shifts or long hours in the office.
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.
After several days of sleep patterns similar to those followed by night workers – three days of night shifts with only four to five hours sleep in 24 hours – the mice lost 25% of the brain cells, in part of the brain stem.
The researchers say this is the first evidence that sleep loss can lead to a loss of brain cells.
Prof Sigrid Veasey of the Center for Sleep and Circadian Neurobiology, told BBC News: “We now have evidence that sleep loss can lead to irreversible injury. No one really thought that the brain could be irreversibly injured from sleep loss”.
However, more work needs to be done on humans, she said. And her group is planning to study deceased shift workers to see if they have the same kind of nerve damage.”This might be in a simple animal but this suggests to us that we are going to have to look very carefully in humans.”
They hope their research will result in medicines that will help people working odd hours cope with the consequences of irregular sleep and protect the brain from the side-effects of lost sleep by boosting a natural chemical involved in sleep recovery.
Prof Hugh Piggins of the University of Manchester said the experiment indicated in a mouse model of sleep deprivation what might go wrong in the human brain.
“The authors draw parallels with night shift work in humans and suggest how chronic sleep deprivation could adversely affect not only our physical, but also our mental health,” he said.
“This possibility will need to be tested by a lot more research. Nonetheless, it is consistent with many recent reports of importance of circadian clocks and sleep cycles for optimal well-being. “
Researchers at Temple University’s School of Medicine believe chronic sleep disturbances could also speed up the onset of dementias and Alzheimer’s disease in older adults. Chronic sleep disturbances can be caused by factors like insomnia, overnight work shifts, and other health conditions.
To determine the relationship between dementia and sleep disturbances, researchers studied two groups of mice in an eight-week pre-clinical study, The Huffington Post reports. Both groups of mice were at the human age equivalent of 40 years. One group was kept on an adequate sleep schedule while the other received excess light hours, significantly reducing their sleep time.
“At the end of the eight weeks, we didn’t initially observe anything that was obviously different between the two groups. However, when we tested the mice for memory, the group which had the reduced sleep demonstrated significant impairment in their working and retention memory, as well as their learning ability,” researcher Domenico Praticὸ said in a release.
The sleep-deprived mice were found to have more tangles in their brain cells. These tangles can disrupt signals between cells, leading to major brain impairment.
“This disruption will eventually impair the brain’s ability for learning, forming new memory and other cognitive functions, and contributes to Alzheimer’s disease,” Praticὸ said.
Sleep deprivation is a major health concern nationally, with an estimated 50-70 million adults suffering from some sort of sleep disorder, according to the Centers for Disease Control. Insufficient sleep can impede daily life activities by lowering concentration, blunting your memory, and even affect your focus while driving. Some studies have even shown that sleep deprivation in older men can increase their risk of premature death.