When people do not get enough sleep, they tend to make overly optimistic decisions and may be more prone to risky gambling, U.S. researchers said.
The study published in the journal Neuroscience provides scientific evidence for what casino managers have long known -- that flashing lights and ringing slot machines encourage gamblers to keep going until their money is gone.
Scientists used magnetic resonance imagining (MRI) to examine the brains of people who had spent a night of disturbed and shortened sleep compared to their better-rested counterparts.
The scans showed increased activity in the parts of the brain that assess positive outcomes, and decreased activity in the areas that process negative outcomes.
"Using a risky decision-making task, we showed that sleep deprivation shifted most persons' bias from avoiding loss to pursuing gain," said the study by Duke University researchers in North Carolina and Singapore.
The study examined 29 healthy adult volunteers with an average age of 22, and asked them to perform a series of economic decision-making tasks after a normal night of sleep and again after a night of sleep deprivation.
Sleep deprivation "appears to create an optimism bias; for example, participants behave as if positive consequences are more likely (or more valuable) and as if negative consequences are less likely (or less harmful)," it said.
Drinking caffeine, getting fresh air or exercising are not enough to combat the effects of fatigue, said lead author Vinod Venkatraman, a graduate student in Psychology and Neuroscience at Duke.
"Late-night gamblers are fighting more than just the unfavorable odds of gambling machines; they are fighting a sleep-deprived brain's tendency to implicitly seek gains while discounting the impact of potential losses," Venkatraman said.