People who suffer chronic sleep problems are more likely to think about suicide or actually try to kill themselves, researchers said on Wednesday.

The more types of sleep disturbances a person had — such as waking up too early, difficulty falling asleep or lying awake at night — upped the odds of suicidal thoughts, planning a suicide, or attempting it, researchers told a conference.

"People with two or more sleep symptoms were 2.6 times more likely to report a suicide attempt than those without any insomnia complaints," Marcin Wojnar, a researcher at the University of Michigan in Ann Arbor and the Medical University of Poland, who led the study, said in a statement.

"This has implications for public health as 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."

According to the World Health Organization, some 877,000 people worldwide kill themselves each year. For every suicide death, anywhere from 10 to 40 attempts are made, the U.N. agency estimates.

Scientists have linked sleep disturbances to increased suicidal risk in people with psychiatric disorders and in adolescents but it is unclear whether the association also exists in the general population, the researchers said.

In the study presented at the World Psychiatric Association International Congress in Florence, Italy, Wojnar and colleagues looked at the relationship between sleep problems and suicidal behaviours among 5,692 U.S. men and women.

About a third of the volunteers reported at least one type of sleep disturbance over the preceding year, which included either difficulty falling asleep, trouble staying asleep or waking at least two hours earlier than desired.

After adjusting for factors such as substance abuse and depression as well as for the influence of age, gender, marital and financial status, the researchers found the most consistent suicide link with waking up early.

People who reported that problem were twice as likely to have had suicidal thoughts or planned a suicide and were nearly three times more likely to have tried to kill themselves.

The researchers do not know exactly why but said lack of sleep may affect cognitive function and lead to poorer judgment and increased hopelessness. A malfunction involving the brain chemical serotonin may also play a role, Wojnar added.

"Our findings also raise the possibility that addressing sleep problems could reduce the risk of suicidal behaviours," Wojnar said.