Most couples know you should never go to bed on an argument.

But anger won't just harm your relationship - it could also ruin your sleep, researchers claim.

A study has found those who were angry generally, and struggled to keep their temper, slept worse, The Daily Mail reports.

They are believed to keep themselves awake by dwelling on their frustrations and find it harder to achieve the calmness they need to drop off. There may even be a physical reason, as feelings of anger increase cardiovascular activity, which makes it harder to fall asleep.

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Psychologists from Iowa State University based their findings on 436 volunteers whose sleep was monitored after completing an anger questionnaire.

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.