Participants were put into two groups at random: one where subjects restricted amount of sleep by 2-4 hours each night for 2 nights; and another who maintained regular sleep schedules. Those in the regular sleep group maintained on average 7 hours of sleep per night; the restricted group got about 4-5 hours of sleep per night on average; which reflects sleep loss experienced in regular day to day life.
Anger was measured before and after sleep manipulation by rating different products while listening to brown noise or more adverse white noise to create uncomfortable conditions that tend to provoke anger.
Sleep was found to impact anger, not just from feeling more negative in the moment, as subjective sleepiness was tested for to explain more intense feelings of anger; sleepiness was found to account for 50% of the experimental effects of sleep restriction on anger, suggesting sense of sleepiness may point to whether a person is likely to become angered.
A separate study is being conducted analyzing data from college students to demonstrate whether the experimental evidence in lab extends to daily life; initial results show that students consistently reported more anger than normal of days when they are experiencing lack of sleep.
The team is gathering data to investigate whether sleep loss causes actual aggressive behavior towards others based on these results.
