Adults who suffer chronic sleep problems may be more likely to try to commit suicide, US research suggests. Doctors are being warned to be vigilant if a patient reports disturbed sleep - even if they have no history of mental health problems. The more types of sleep disturbances people had, the more likely they were to have thoughts of killing themselves, or actually try to do so. The study will be presented at a World Psychiatric Association meeting. The World Health Organization estimates that about 877,000 people worldwide die by suicide every year. For every death up to 40 suicide attempts are made. Scientists have consistently linked sleep disturbances to an increased risk of suicidal behaviour in people with psychiatric disorders and in adolescents. But it has been unclear whether the association also exists in the general adult population. Sleep disturbance A University of Michigan team examined the relationship over one year between sleep problems, and suicidal behaviour in 5,692 Americans. During the course of the year 2.6% of the sample had suicidal thoughts, and 0.5% were recorded as making a suicide attempt. They looked at three types of sleep problems - difficulty falling asleep, difficulty staying asleep and waking at least two hours earlier than desired. The researchers took account of factors such as substance abuse, depression, anxiety disorder, and physical illness, as well as social factors such as marriage and financial status. People with two or more symptoms of insomnia were 2.6 times more likely to report a suicide attempt than those whose sleep was not disturbed. Early morning waking was the single trait most strongly linked to suicidal behaviour. Lead researcher Dr Marcin Wojnar said: "The presence of sleep problems should alert doctors to assess such patients for a heightened risk of suicide even if they don't have a psychiatric condition. "Our findings also raise the possibility that addressing sleep problems could reduce the risk of suicidal behaviours." Underlying link Dr Wojnar said it was possible that sleep disorders and suicidal thoughts were both the manifestation of a troubled psyche, or that poor sleep drove people to thoughts of suicide. But he also suggested there could be an underlying physiological link between the two which was not clear. Experts have suggested that a lack of sleep might affect the way the brain works, leading to poor judgement and less ability to control impulses. It is also suspected that both sleep disorders and suicidal thoughts might be linked to an imbalance in the chemical serotonin, which plays a key role in regulating mood. Dr Daniel Freeman, of the Institute of Psychiatry at King's College London, said the study showed that insomnia was very common, and could have a significant effect on psychological well-being. He said: "It is very plausible that suicidal thoughts, which happen when we are depressed and find it hard to think our way out of our problems, have been linked to insomnia. "However it needs to be remembered that insomnia is very common and suicidal thoughts less so. Most people with insomnia manage the effects very well. "Insomnia only triggers severe problems for people with a pre-existing vulnerability." Sleep important Dr Neil Stanley, a sleep expert at Norfolk and Norwich University Hospital, said: "This study reinforces the fact that good sleep is vital for good physical, mental and emotional health. "Poor sleep has long been linked with an increased risk of depression, but this study suggests that the increased risk of suicidal behaviour is not necessarily linked to depression and thus can affect those that doctors might not feel are at risk. "It is another demonstration of the importance, both as an individual and as a society, of getting good sleep." Source: BBC