22 Jan Restriction of sleep augments angry feeling
This investigation, done by Zlatan Krizan and Garrett Hisler at Iowa State University, has an objective to test whether mild levels of sleep loss, commonly experienced in daily life, can cause anger. To address some gaps in previous investigations (lack of provocation, small sample sizes, and neglect of potential mediators). They conducted a test on the influence of everyday doses of sleep loss on anger.
The research, published in the Journal of Experimental Psychology, in general, answers those questions and provides insight on our ability to adjust to irritating conditions when tired. Firstly, they wanted to induce a moderate amount of sleep restriction, about 5 to 6 hr overall, which reflects an amount of sleep loss frequently experienced in everyday life.
Secondly, they examined anger during differing levels of provocation (i.e., trials with less vs. more aversive noise). Thirdly, they recruited a large sample size (more than 150 individuals) and assessed anger both before and after the manipulation of sleep, ensuring higher precision and enabling a direct examination of how sleep restriction impacts changes in anger throughout sleep loss. Finally, they examined whether subjective sleepiness may account for anger changes due to sleep loss.
Study participants were randomly split into two groups: one maintained their normal sleep routine and the second restricted their sleep by 2 to 4 hours each night for two nights. Those who maintained averaged almost 7 hours of sleep a night, while the restricted group got about 4.5 hours each night. The difference reflects sleep loss we regularly experience in everyday life, Krizan says.
Using actigraphy they monitored sleep-wake periods in the participants during two nights. Once back at the lab following the two nights at home, the participants returned the Actiwatch and completed a short, printed questionnaire assessing sleepiness (via Stanford and Epworth Sleepiness scales) and adherence to at-home instructions (use of alcohol, drugs, caffeine, or any naps over the past two days). Then, participants again first completed the randomly ordered cognitive assessments, before completing the randomly ordered anger, affect, and perceived hostility measures.
To measure anger, the 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 says the purpose was to create uncomfortable conditions, which tend to provoke anger. “In general, anger was substantially higher for those who were sleep restricted,” Krizan says. “We manipulated how annoying the noise was during the task and as expected, people reported more anger when the noise was more unpleasant. When sleep was restricted, people reported even more anger, regardless of the noise.”
The results revealed that losing even moderate amounts of sleep can make a person angrier. Despite typical tendencies to get somewhat used to irritating conditions, sleep-restricted individuals actually exhibited a trend toward increased anger, reversing normal adaptation. These patterns merged with broader changes in affect and were directly dependent on subjective sleepiness of the individual. Finally, there were minimal effects on cognitive appraisals of hostility, highlighting the importance of sleep for emotional experiences.
Conclusion: Intuitions about frustrations following sleep loss are commonplace, but sleep science has only recently delved into sleep’s role in anger. In a large group of adults, those who restricted their sleep saw near-increases in anger during noise, instead of decreases, as did their more well-rested counterparts. Subjective sleepiness accounted for most of the impact that sleep loss exerted on anger, pointing to an apparent paradox: One can be both sleepy and angry at the same time.
- Krizan Z, Hisler G. Sleepy anger: Restricted sleep amplifies angry feelings. J Exp Psychol: Gen 2019 07;148(7):1239-1250.
- Sleep Restriction Intensifies Anger. Published on October 11, 2019 in sleep Review. The journal for sleep specialist. Available online: http://www.sleepreviewmag.com/2019/10/sleep-restriction-intensifies-anger/