When deprived of sleep, some people are able to cope and respond much better than others. Although scientists have identified genes associated with this phenomenon, it was still unknown why the effects of sleep deprivation tend to vary so widely across both individuals and cognitive tasks.
For example, after a day without sleep, some people might struggle with a reaction time test but perform well on decision-making tasks, or vice versa.
Now, in a new study published in the journal Scientific Reports, researchers at Washington State University have identified a genetic variation that significantly impacts how well sleep-deprived individuals perform mental tasks.
The findings show that people with a particular variation of the DRD2 gene are resilient to the effects of sleep deprivation when performing tasks that require cognitive flexibility, the ability to make appropriate decisions based on changing information.
However, sleep-deprived people with two other variations of this same gene tend to perform much more poorly on the same kinds of tasks.
The DRD2 dopamine receptor gene impacts the processing of information in the striatum, a region of the brain commonly associated with cognitive flexibility.
“Our work shows that there are people who are resilient to the effects of sleep deprivation when it comes to cognitive flexibility,” said Paul Whitney, a Washington State University (WSU) professor of psychology and lead author of the study. “Surprisingly these same people are just as affected as everyone else on other tasks that require different cognitive abilities, such as maintaining focus.”
“This confirms something we have long suspected, namely that the effects of sleep deprivation are not general in nature, but rather depend on the specific task and the genes of the person performing the task.”
In the new study, Whitney, along with colleagues John Hinson, WSU professor of psychology, and Hans Van Dongen, director of the WSU Sleep and Performance Research Center at WSU Spokane, compared how people with different variations of the DRD2 gene performed on tasks designed to test both their ability to anticipate events and their cognitive flexibility in response to changing circumstances.
The study recruited 49 adults to participate at the WSU Spokane sleep laboratory. After a 10-hour rest period, 34 participants were randomly selected to go 38 hours without sleep while the others were allowed to sleep normally.
Before and after the sleep deprivation, subjects viewed a series of letter pairings on a computer screen and were told to click the left button for a certain letter combination (e.g., an A followed by an X) and the right button for all other letter pairs. After a while, both the sleep-deprived group and the non-sleep deprived group were able to identify the pattern and click correctly for various letter pairs.
The task became trickier. In the middle of the test, researchers told the participants to now click the left button for a different letter combination. The sudden switch stumped most of the sleep-deprived participants, but those who had a particular variation of the DRD2 gene handled the switch as well as they did when well-rested.
“Our research shows this particular gene influences a person’s ability to mentally change direction when given new information,” said Van Dongen. “Some people are protected from the effects of sleep deprivation by this particular gene variation but, for most of us, sleep loss does something to the brain that simply prevents us from switching gears when circumstances change.”
The effects of sleep deprivation on cognitive flexibility can have serious consequences, particularly in high stakes, real-world situations like an emergency room or military operations where the ability to respond to changing circumstances is vital.
The researchers are currently applying what they’ve learned from their study to develop new ways to help surgeons, police officers, soldiers and other individuals who regularly deal with the effects of sleep deprivation in critical, ever-changing settings cope with the loss of cognitive flexibility.
“Our long-term goal is to be able to train people so that no matter what their genetic composition is, they will be able to recognize and respond appropriately to changing scenarios, and be less vulnerable to sleep loss,” said Whitney. “Of course, the more obvious solution is to just get some sleep, but in a lot of real-world situations, we don’t have that luxury.”
Source: Washington State University