Bad dreams may not be all bad news. Research has suggested that nightmares could be part of a psychological mechanism for coping with the trials of life, writes Steve Farrar.
A study of 412 students has found a link between stress - from problems at work to the death of a loved one - and the frequency and intensity of bad dreams.
While the number of nightmares tended to be lower for those with strong social support, it appeared to be higher among those who sought to cope with stress during the day.
Volunteers underwent standard psychological tests to determine the level of stress they were experiencing, the degree to which they were coping with it and the social support they had, as well as assessing the nightmares they suffered.
The researchers, led by Dante Picchioni, a doctorate student at the University of Southern Mississippi in the US, concluded: "These findings raise the intriguing possibility that nightmares and coping are related because they serve similar functions." Mr Picchioni said: "No one would think that nightmares serve a beneficial function, but this research suggests that they might do just that."
There are a number of theories as to how this might work. Bad dreams could help desensitise an individual's fear of situations, perhaps help solve emotional problems or maybe rehearse a stressful scenario that is preying on a person's mind.
Robert Hicks, professor of psychology at San Jose State University, where Mr Picchioni carried out the research, said: "Some think dreams are just 'noise'. I think some have importance."
The research focused on by far the most common type of nightmare, which is suffered during the rapid eye movement phase of sleep and can often be recalled on waking.
The findings are published in the journal Dreaming .