Writing in the Journal of Research in Personality, they state: "These findings add to the growing evidence that being prone to anger may lead to poor sleep and that anger and sleep are intimately connected."
Study participants were asked questions designed to determine if they were quick-tempered and became angered easily. They were asked how angrily they would react to specific provocations, such as being criticised by others.
Finally they were sorted into groups based on how they dealt with anger - the "anger-in" group, the "anger-out" group and people with "anger-control".
The people who controlled their anger, saying they would "keep my cool" under pressure, got better quality sleep during a week of being tracked.
But those who repressed their rage, within the "anger-in" group, got worse sleep by comparison. The study showed those who did not let their anger out by saying "nasty things", but instead chose to "boil inside" still lost out on sleep.
Previous research has suggested that people are angry because they lose out on sleep, which makes it harder to hold back negative emotions and creates a vicious circle.