Sleep deprivation leads to risky decisions, study finds

A recent study finds that a sleep-deprived person is more focused on positive outcomes in decision making, which could result in greater risks.
A recent study finds that a sleep-deprived person is more focused on positive outcomes in decision making, which could result in greater risks.

When visiting Las Vegas, beware the temptation to spend a late night in the casinos, a new study on decision making warns.

In a study conducted in Singapore, researchers at Duke and the Duke-National University of Singapore Graduate Medical School found that sleep-deprived people make riskier decisions based on inaccuracies in perceived gains and losses. This study provides the first evidence that sleep changes how the brain evaluates economic value.

“People who are well rested avoid outcomes that have very high losses,” said Vinod Venkatraman, a primary author of the study and Duke fifth-year graduate student in psychology and neuroscience. “When that same individual is sleep deprived, the individual tends to focus more on the gains and doesn’t care as much about the losses.”

The study, titled “Sleep Deprivation Biases the Neural Mechanisms Underlying Economic Preferences,” appeared in the March 9 issue of The Journal of Neuroscience. It featured twenty-nine subjects with an average age of 22.34, who were given win-loss scenarios such as, “[Would] you want to choose an option that gives you a 30 percent chance of making $80, a 40 percent chance of losing $50 [or] a 30 percent chance of making $0?”

The subjects answered a series of similar questions twice, once after sleeping between seven to nine hours and once after not sleeping for an entire night.

Researchers found that when sleep deprived, the subjects displayed increased activity in the ventromedial prefrontal cortex, the part of the brain that focuses on positive outcomes when making decisions. These subjects also displayed decreased activity in the anterior insula, which focuses on negative outcomes, so that whereas well-rested people generally look to minimize losses, sleep-deprived individuals may instead seek to maximize gain. These variations in activity occurred when subjects made their decisions and after they discovered the financial outcomes of their decisions.

Venkatraman said the effect of sleep deprivation on how people assign value to information is independent from its effect on attention and fatigue, a key discovery in studies on sleep deprivation and decision making.

“For example, if you are tired, caffeine may boost your attention, but this will not necessarily change your evaluation,” Venkatraman said. “Our study is the first to show that.”

Michael Chee, a cognitive neuroscience professor at Duke-NUS Graduate Medical School, led this study and a similar study that was conducted in 2007. The earlier study showed differences in brain activation similar to those of the recent study.

“The finding that the brain is responsive to the promise of reward... has now been replicated in two risky decision making studies, which suggests that sleep deprivation has a real effect,” Chee said. “This is important because some other groups have had variable results.”

Scott Huettel, associate professor of psychology and neuroscience at Duke, led the decision making lab with Chee and said the study reveals more reasons why gambling is dangerous.

“Casinos often take steps to encourage risk-seeking behavior by providing alcohol, introducing flashy lights and sounds and converting money to chips or electronic credits,” Huettel wrote in an e-mail. “Sleep deprivation surely exacerbates these effects, making gambling even more tempting for many individuals.”

The study’s findings also have implications that extend beyond gambling.

“Most people consider sleep an optional thing that you can disregard easily, but we beg to differ,” Chee said. “This study should grab people’s attention and show that you are not the same person if you deprive yourself of sleep for one night.”


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