People experiencing chronic insomnia may have more than three times the risk of developing asthma compared to those without the disorder, a new study has warned.
Asthma affects about 300 million people worldwide, with major risk factors including smoking, obesity and air pollution, researchers said.
More recently, symptoms of depression and anxiety have been associated with a risk of developing asthma in adulthood.
"Insomnia, defined as having difficulties initiating or maintaining sleep, or having poor sleep quality, is common among asthma patients, but whether insomnia patients have a higher risk of developing asthma at a later stage has not been thoroughly investigated," said Linn Beate Strand from Norwegian University of Science and Technology (NTNU).
The researchers used statistical analysis to assess the risk of asthma among 17,927 participants aged between 20 and 65 years.
Participants were asked to report sleep initiation problems, sleep maintenance problems and poor quality sleep. They also reported any asthma symptoms at the start and at the end of the study.
The results showed that those participants reporting difficulty falling asleep "often" or "almost every night" during the last month had a 65 per cent and 108 per cent increased risk of developing asthma over the following 11 years, respectively.
Similarly, those who reported waking too early without being able to go back to sleep "often" or "almost every night" had a 92 per cent and 36 per cent increased risk of developing asthma.
For people who reported poor quality sleep more than once a week, the risk of developing asthma increased by 94 per cent.
When the researchers looked at patients with chronic insomnia, ie they had reported one or more insomnia symptom at the start of the study and ten years earlier, they found that those with chronic insomnia had over three times the risk of developing asthma compared to those without chronic insomnia.
"A key finding in our study is that those people with chronic insomnia had more than three times the risk of developing asthma, compared to those without chronic insomnia, which suggests that any changes in the body due to insomnia may accumulate and result in more severe harmful effects on the airways," said Ben Brumpton, from Department of Public Health and General Practice, NTNU.
"As insomnia is a manageable condition, an increased focus on the adverse health effects of insomnia could be helpful in the prevention of asthma," Strand added.
The study was published in the European Respiratory Journal.