by VR Sreeraman on  June 28, 2009 at 10:58 AM Research News
 Why Sleep Deprivation Affects Some People More Than Others
Conducting a new imaging research, scientists have explained why sleep deprivation affects some people more than others.

Researchers observed that people who are genetically vulnerable to sleep loss showed reduced brain activity after staying awake all night, while those who are genetically resilient showed expanded brain activity.

The findings help explain individual differences in the ability to compensate for lack of sleep.

"The extent to which individuals are affected by sleep deprivation varies, with some crashing out and others holding up well after a night without sleep," said Dr. Michael Chee, at the Duke-National University of Singapore Graduate Medical School.

In the current study, the researchers, led by Dr. Pierre Maquet, at the University of Liege in Belgium selected study participants based on their genes.

Previous research showed that the PERIOD3 (PER3) gene predicts how people will respond to sleep deprivation. People carry either long or short variants of the gene.

Those with the short PER3 variant are resilient to sleep loss - they perform well on cognitive tasks after sleep deprivation.

However, those with the long PER3 variant are vulnerable - they show deficits in cognitive performance after sleep deprivation. Now the new study explains why.

The authors imaged study participants while they did a working memory task that requires attention and cognitive control - also called executive function.

They found that the resilient, short gene variant group compensated for sleep loss by "recruiting" extra brain structures.

Besides brain structures normally activated by the cognitive task, these participants showed increased activity in other frontal, temporal, and subcortical brain structures after a sleepless night.

On the other hand, after a sleepless night, vulnerable participants, the long PER3 group, showed reduced activity in brain structures normally activated by the task.

These participants also showed reduced brain activity in one brain structure - the right posterior inferior frontal gyrus - after a normal waking day.

The above data is consistent with previous research suggesting that people with the long gene variant perform better on executive tasks earlier, but not later, in the day.

"Our study uncovers some of the networks underlying individual differences in sleep loss vulnerability and shows for the first time how genetic differences in brain activity associate with cognitive performance and fatigue. The data also provide a basis for the development of measures to counteract individual cognitive deficits associated with sleep loss," said study author Maquet.

The study is published in the latest issue of The Journal of Neuroscience.

Source: ANI

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