Scientists have discovered a link between snoring and headaches.
Constant headaches can be very debilitating
Tests on patients in the United States have found that people who suffer from regular headaches are also more likely to snore at night.
However, they are unable to say whether snoring triggers headaches or whether headaches cause people to snore.
Nevertheless, the discovery could provide scientists with further clues for helping people who suffer from severe headaches.
Scientists at the US National Institute on Aging studied 206 people between the ages of 18 and 65 who had suffered from chronic daily headaches for five years or less. They were compared to 507 people who only suffered from occasional headaches.
Chronic daily headache was defined as people with at least 15 headaches each month while occasional headache was defined as between two and 104 headaches per year.
In this study, those with chronic daily headache suffered an average of 260 attacks each year. Those with occasional headaches had an average of 24 headache days per year.
The participants were asked how often they snored. The researchers found that patients with chronic daily headache were twice as likely to also be chronic snorers compared to those who only suffered from headaches occasionally.
The result was the same even when adjusting for factors that can affect breathing in sleep, such as body weight and alcohol intake.
The researchers said further study is needed to determine why people who suffer from chronic daily headaches are more likely to snore.
"The headaches could be causing the snoring or the snoring could be causing the headaches, or both," said Dr Ann Scher, who led the research.
"Chronic headache can result in disturbed sleep and sedating medications used to treat pain can aggravate sleep-disordered breathing.
"On the other side, sleep deprivation or excessive sleep can trigger migraine attacks in some people."
But Dr Scher added that the discovery could help scientists to develop treatments for people who suffer from chronic headaches.
"If we can show that the snoring is causing the headaches, then we may be able to stop or lessen people's headaches by treating their snoring," she said.
"This would be a great relief to people who suffer from chronic daily headache."
Dr Peter Goadsby of The Headache Group at the Institute of Neurology in London, said chemical changes in the brain may trigger headaches.
"People who have problems sleeping at night may also retain carbon dioxide. This causes chemical changes in the blood which in turn can cause headaches," he told BBC News Online.
The study is published in the journal Neurology.