Scientists confirm it: Too little sleep makes you angry

Sometimes scientific research unveils to us the new and the wondrous. On other occasions, it confirms the blindingly obvious.

Here’s something that any shift worker or the parents of a young child could have told you: Lack of sleep makes us angry.

Compelling evidence it ‘amplifies anger’

A scientific study published in Sleep, the academic journal of the Sleep Research Society – and entitled ‘Does Losing Sleep Unleash Anger?’ – determined that “there is compelling evidence that lost sleep amplifies anger in both the laboratory and everyday life”.

To reach this conclusion, researchers examined the daily diary entries of 202 college students who tracked their sleep, daily stressors and anger levels over one month.

They also tested 147 members of the public in a laboratory environment. Some of the participants were asked to maintain their regular sleep patterns, while others had to reduce their normal sleep quota by five hours across two nights.

Irritating noises were … very irritating

For the college student group, it was very clear that they experienced a higher level of anger if they’d had less sleep the night before.

For the second group of members of the public, the researchers tested their anger by playing irritating noises to them.

Those participants who had slept normally were less likely to react negatively. But those with reduced sleep showed notably increased anger at the noises.

Increases both anger and frustration

“The results are important because they provide strong causal evidence that sleep restriction increases anger and increases frustration over time,” said Zlatan Krizan, Professor of Psychology at Iowa State University in the US.

“Moreover, the results from the daily diary study suggest such effects translate to everyday life, as young adults reported more anger in the afternoon on days they slept less.”

The results back up the finding of a study by the University of Pennsylvania, also in the US. Its researchers found that subjects who were limited to only 4.5 hours of sleep a night for one week reported feeling more stressed, angry, sad and mentally exhausted. When the subjects resumed normal sleep, they reported a dramatic improvement in mood.

Now go away and leave me alone. I had a bad night’s sleep last night.