Australian researchers have quantified the link between smoking and silent killer sleep apnoea in a world first.

To achieve the breakthrough, scientists from Sydney's Heart Research Institute established a connection between quantities of nicotine in the blood and the amount of time people are deprived of oxygen while sleeping.

Sleep apnoea occurs when a person's throat and upper airway become partly or completely blocked, causing short periods where breathing stops.

Smokers are three times more likely to experience the disorder, which is generally estimated to affect up to one-third of the adult population, or one billion people worldwide.

Lead researcher Dr John O'Sullivan says his team found increases in nicotine levels were associated with a 2.3-minute increase in time spent with oxygen saturations below 90 per cent, a key marker of apnoea severity.

This means that for every cigarette a person smokes, they are more likely to have "dangerously low" levels of oxygen.

"People who spend more time with an oxygen saturation less than 90 per cent end up with more cardiovascular death than people who don't," Dr O'Sullivan said, referring to smoking and non-smoking populations.

"Although smoking is known to reduce oxygen concentration in the blood, the interaction of smoking with sleep apnoea has not been quantified," he said.

"Using blood concentrations of the major nicotine metabolite, we were able for the first time to quantify the effect."

In terms of research outcomes, Dr O'Sullivan noted that "stiff heart failure", when the heart muscle can still pump blood but can't relax properly, is the most common form of heart failure.

However, there are almost no treatment options.

Metabolomics is a relatively new field of study that investigates metabolites or metabolism components that play key roles in disease.

As was the case in the HRI project, they can provide insight into how one disease is linked to another.

To arrive at its findings, the team studied metabolites and lipids in 1919 people from the long-running US Framingham Heart Study and 1524 participants of another, the Women's Health Initiative.

The results are published in the medical journal ESC Heart Failure Today.