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If you don’t get enough sleep, it’s possible that you’ll get brain damage, according to a recent Penn study.

The study, conducted by Professor of Medicine Sigrid Veasey over the past year, examined the effects of restricting sleep in mice. It showed that restricting sleep in mice results in loss of brain neurons.

The mice were kept awake for eight hours over a period of a few days during times when they would normally be asleep. Afterwards, the mice were allowed to sleep normally. Once the experiment was finished, the mice were euthanized and their brains were examined.

After examining images of the mice’s brains, Veasey found that the mice had lost neurons, but that there was no physical injury to their brains. However, since neurons cannot regenerate, the mice would have sustained long-term brain damage, she said.

Specifically, the brain slices were stained and the number of remaining neurons were counted in the locus coereleus — an area of the brain responsible for regulating attention, mood and sleep-wake cycles, as well as integrating facts and information.

Veasey explained that the mice lost 25 percent of their brain cells and lost connections between the locus coereleus and the control center — or cortex — of the brain.

Although the study found cell loss in mice, the results cannot directly be translated into humans. Veasey is continuing to research whether or not the brain can recover from this loss of sleep and whether there are protective mechanisms that can prevent brain damage resulting from sleep loss.

The recent study was developed following the results of a test conducted on college students, designed by psychology professor David Dinges , to measure attention after reduced sleep. It found students had lapses in attention and worsening performances when deprived of sleep.

“Once they had their first night of recovery — and even after a full three nights of recovery — they still had attention lapses, “ Veasey said. “This suggests that there is some residual injury to attention.”

The mice experiment was performed on animals so that investigators could examine their brains in detail and understand the underlying mechanism of sleep deprivation and its consequences.

Veasey said her biggest concern for humans was that if people “burn out” their locus coereleus due to lack of sleep, they could potentially become depressed.

“The role [of the locus coereleus] in mood is incredibly important, whether it’s frank depression or just where you don’t feel like doing anything — neither of these is good,” she said.

College junior Max Wang , who works in Veasey’s lab and was directly involved with the study, said that he wasn’t very surprised at the results.

“It should be evident that sleep is important and I think that people like to kid themselves that it’s not very necessary,” Wang said. “I think it gives more people an incentive to value sleep more.”

Veasey said that people don’t realize it takes a long time to recover from sleep loss, and she wonders how much sleep loss could lead to “irreversible” damage.

Dinges, who also studies sleep and the consequences of inadequate sleep, said that the impact on the brain not only depends on how much sleep is lost, but also the method of sleep deprivation as well.

“Part of it comes down to whether the method of sleep deprivation contributed stress that may have ... contributed to effects separate [from] sleep loss per se,” Dinges said.

Both Dinges and Veasey agree that this evidence has implications for shift workers who operate in a daytime society but must also stay awake for night shifts.

“They suffer the dual problem of sleep being displaced into the daytime when humans are normally awake and the circadian clock” — a mechanism that determines a person’s sleep cycle — “which makes it harder for us to sleep in the daytime,” Dinges said.

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