The study showed that those patients who complained of nightmares during the week following the suicide attempt were three times more likely to attempt to take their own life again, regardless of gender or psychiatric diagnosis, such as depression or post-traumatic stress syndrome.

During the study, the researchers recruited 165 patients aged 18-69 years, who were being treated at somatic and psychiatric departments following a suicide attempt.

"Those who were still suffering from nightmares after two months faced an even greater risk,” said Registered Nurse Nils Sjostrom, author of the study,

“These people were five times more likely to attempt suicide a second time,” she added.

People who have attempted suicide often suffer from sleeping difficulties. Some 89 percent of the patients in the study reported some kind of sleep disturbance.

The most common problems were difficulty in initiating sleep, followed by difficulty in maintaining sleep, nightmares and early morning awakening.

She has also examined the possibility of being an increased risk of repeat suicide attempts if the patient has difficulty falling asleep, difficulty sleeping during the night, or wakes up early in the morning.

However, the result did not indicate any increased risk.