Sleep Loss Unleashes Anger

Megan Brooks

September 15, 2020

A good night's sleep may be important for anger management in new findings that suggest sleep loss amplifies frustration.

In a series of studies, researchers found that sleep loss consistently increased anger in response to environmental frustration, competitive interactions, and everyday moments.

"Disrupted sleep can contribute to anger and undermine adaptation to frustrating conditions," study investigator Zlatan Krizan, PhD, professor of psychology and director of the Sleep, Self, and Personality Laboratory at Iowa State University in Ames, told Medscape Medical News.

"For individuals with anger management problems, sleep loss may be an important trigger or a target for intervention," Krizan added.

The findings were presented at Virtual SLEEP 2020, the 34th annual meeting of the Associated Professional Sleep Societies.

"Strong Causal Evidence"

"The link between anger and sleep has been well-documented, but the reasons for this association remain elusive. In this research, we examined evidence that sleep loss amplifies anger, given it often increases fatigue, irritability, and creates self-control problems," said Krizan.

In one study, the researchers had 202 college students keep a 30-day diary where they reported how long they slept each night; number of daily social, work, and academic stressors; and "state anger." Multilevel modeling was used to estimate within-person effects of prior night's sleep on next-day anger.

The results showed that students experienced more anger on days following less sleep (P < .001). In a separate study, 142 community residents maintained their regular sleep schedule (control group) or restricted their sleep at home by about 4 hours over two weeknights.

Sleep restriction was confirmed via an Actiwatch and a sleep diary. Following this manipulation, anger was assessed during exposure to an irritating noise.

In contrast to the control group, those in the sleep-restricted group exhibited higher and increased anger in response to the aversive noise, suggesting that losing sleep undermined emotional adaptation to frustrating circumstances. Subjective sleepiness accounted for most of the effect of sleep loss on anger.

A related study of 124 individuals who played a competitive online game following sleep restriction showed similar results, with more competitive anger after sleep loss.

"Prior to this study there has only been indirect evidence that sleep [loss] can boost anger, and experimental studies did not create contexts that could actually arouse anger," said Kirzan.

These results provide "strong causal evidence" that sleep restriction increases anger and increases frustration over time, he added.

The Greater Good

Commenting on the findings for Medscape Medical News, Nitun Verma, MD, spokesperson for the American Academy of Sleep Medicine, said there is existing evidence that sleep deprivation is associated with negative mood and anxiety," but it is interesting that this study is targeting a specific negative emotional response — anger."

"Someone with poor sleep can have increased negative emotions, and that affects how they interact with others. It's an example of how the effects of poor sleep can be considered 'contagious.' The public health message? Sleeping well is not just good for you, but everyone around you," said Verma, who was not involved with the study.

Krizan serves as associate editor for Personality and Social Psychology Bulletin, Journal of Research in Personality, and SLEEP Advances. Verma has disclosed no relevant financial relationships.

Virtual SLEEP 2020: 34rd Annual Meeting of the Associated Professional Sleep Societies: Abstract 0276. Presented August 28, 2020.

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