Lack of sound sleep makes people more angry: Study

A new study suggests that sleep-deprived makes you angrier, irritable and loss of calmness. A night of sleep loss affects mood and makes you more hostile, especially in a frustrating situation, a study report.

The research, published in the Journal of Experimental Psychology: General by an American Psychological Association answers those questions and provides new insight on our ability to adjust to irritating conditions when tired.

“Despite typical tendencies to get somewhat used to irritating conditions—an uncomfortable shirt or a barking dog—sleep-restricted individuals actually showed a trend toward increased anger and distress, essentially reversing their ability to adapt to frustrating conditions over time. No one has shown this before,” said Zlatan Krizan, a professor at Iowa State University in the US.

Also Read | Men prefer bromances over romantic relationship reveals this study

Krizan said other studies have shown a link between sleep and anger, but questions remained about whether sleep loss was to blame or if anger was responsible for disrupted sleep.

The study has found people with normal sleep actually had their frustration levels lower from one day to the next because they become accustomed to the annoying noise used to measure anger. On the other hand, people who have troubling sleeping or received lesser hour sleep than normal not only were angrier but actually even more agitated.

“In general, anger was substantially higher for those who were sleeping restricted. We manipulated how annoying the noise was during the task and as expected, people reported more anger when the noise was more unpleasant,” said Krizan.

“When sleep was restricted, people reported even more anger, regardless of the noise and the difference reflects sleep loss we regularly experience in everyday life,” said Krizan.

The researchers were randomly split the participants into two groups: one maintained their normal sleep routine and the second restricted their sleep by two to four hours each night for two nights.

Read More | Not humans, but climate change wiped out shaggy Siberian unicorn about 36,000 years ago

Those who maintained averaged almost seven hours of sleep a night, while the restricted group got about four and a half hours each night.

To measure anger, researchers had participants come to the lab—before and after the sleep manipulation—to rate different products while listening to brown noise (similar to the sound of spraying water) or more aversive white noise (similar to a static signal).

Krizan said the purpose was to create uncomfortable conditions, which tend to provoke anger.

 It is well established that sleep loss increases negative emotions, such as anxiety and sadness, and decreases positive emotions, such as happiness and enthusiasm, Krizan said.

Researchers measured these effects to more generally understand the relationship between sleep, anger and emotions. Krizan said they found sleep loss to uniquely impact anger, and not just result from feeling more negative at that moment.

They also tested whether subjective sleepiness explained more intense feelings of anger.

Sleepiness accounted for 50 per cent of the experimental effect of sleep restriction on anger, suggesting individuals’ sense of sleepiness may point to whether they are likely to become angered, Krizan said.

(With PTI inputs)