Missed Sleep Jolts Mood, Impairs Decision-Making
Not getting enough sleep can lead to short-term euphoria, possibly leading to poor decision-making and risky behavior, according to researchers from the University of California, Berkeley, and Harvard Medical School.
The study revealed that the pleasure circuitry in the brains of volunteers got a jump-start after a missed night’s sleep. However, that same neural pathway that triggers euphoria as well as feelings of reward and motivation may also lead to chancy behavior.
“When functioning correctly, the brain finds the sweet spot on the mood spectrum. But the sleep-deprived brain will swing to both extremes, neither of which is optimal for making wise decisions,” said Dr. Matthew Walker, lead author and associate professor of psychology and neuroscience at UC Berkeley.
The findings emphasize the need for people in critical professions and circumstances not to skip out on sleep, said Walker.
“We need to ensure that people making high-stakes decisions, from medical professionals to airline pilots to new parents, get enough sleep,” Walker said. “Based on this evidence, I’d be concerned by an emergency room doctor who’s been up for 20 hours straight making rational decisions about my health.”
Previous studies have shown that sleep patterns are disrupted in individuals suffering from mood disorders. Typically, the sleeping body alternates between two main phases during the night: Rapid Eye Movement (REM), when body and brain activity promote dreams, and Non-Rapid Eye Movement (NREM), when the brain and muscles rest.
In an effort to understand why so many people with clinical depression tend to feel better after a sleepless night (at least temporarily), scientists used functional magnetic resonance imaging (fMRI)to observe the brains of 27 young adults; half got a good night’s sleep and the other half had none.
Volunteers looked at various images, including pleasant scenes (such as bunnies or ice cream sundaes), and then rated the pictures as either neutral or positive. Across the board, those who had pulled an all-nighter gave more positive scores for all the images while the well-rested volunteers gave more moderate ratings.
In addition, brain scans of the sleepless individuals revealed stronger activity in the mesolimbic pathway, a brain circuit driven by dopamine, a neurotransmitter associated with positive feelings, motivation, addiction, cravings, sex drive and decision-making.
While having a short-term boost in dopamine levels may seem like a good thing, this phenomenon can be dangerous if people are making impulsive decisions because they’re feeling overly optimistic, the study suggests.
The results add to prior research by Walker and his team that show how sleep deprivation shuts down the brain’s key decision-making regions, particularly the prefrontal cortex, while triggering more primal mechanisms such as the fight-or-flight reflex in the amygdala.
“After a good night’s sleep, the frontal lobe regions are strongly connected to the dopamine reward regions, but that’s not the case after a night of no sleep,” Walker said.
According to Walker, sleep deprivation is not a viable solution for those with clinical depression. “The elastic band of sleep deprivation can only be stretched so far before it breaks,” he said.
The study is published in the Journal of Neuroscience.
Source: University of California
Pedersen, T. (2011). Missed Sleep Jolts Mood, Impairs Decision-Making. Psych Central. Retrieved on August 31, 2015, from http://psychcentral.com/news/2011/03/26/missed-sleep-jolts-mood-impairs-decision-making/24627.html