(Australian Associated Press)

The combination of poor sleep and lack of exercise is a double whammy that’s putting people at great risk of developing life-threatening diseases, according to a University of Sydney study.

The large long-term study that’s published in the British Journal of Sports Medicine on Wednesday, found “a likely synergy between physical activity and sleep”.

Both physical inactivity and poor sleep have independently been associated with a heightened risk of death and cardiovascular disease and cancer, but it hasn’t been clear if they might have a combined effect on health.

“We found those who had both the poorest sleep quality and who exercised the least were most at risk of death from heart disease, stroke, and cancer,” lead author and PhD candidate Bo-Huei Huang said.

Senior author and research program director, Professor Emmanuel Stamatakis said the research was particularly pertinent because “sadly, our society suffers from both a physical inactivity and a poor sleep crisis”.

“Considering that physical activity is perhaps more modifiable than sleep, our study offers people more health incentives to be physically active and provides health professionals with more reasons to prescribe physical activity to patients with sleep problems,” he said.

The researchers drew on information provided by 380,055 middle-aged men and women taking part in the UK Biobank study the long the long-term health of more than half a million 37 to 73-year-olds, who were recruited between 2006 and 2010.

Participants’ health was tracked for an average of 11 years up to May 2020 or death, to assess their risk of dying from any cause as well as from all types of cardiovascular disease, coronary heart disease, stroke, cancer and lung cancer.

Those who were younger, female, had lower body mass index, were better off financially, ate more fruit and vegetables, spent less of their day seated, had no mental health issues, never smoked, didn’t work shifts, drank less alcohol and were more physically active tended to have healthier sleep scores.

The lower the sleep score, the higher were the risks of death from any cause, from all types of cardiovascular disease, and from ischaemic stroke.

Compared with those with the high physical activity and healthy sleep score combination, those at the other end of the scale, with the no moderate to vigorous physical activity and poor sleep combination, had the highest risks of death from any cause (57 per cent higher).

They also had the highest risk of death from any type of cardiovascular disease (67 per cent higher), from any type of cancer (45 per cent higher), and from lung cancer (91 per cent higher).

Lower levels of physical activity amplified the unfavourable associations between poor sleep and all health outcomes, except for stroke.

The researchers concluded that physical activity levels at or above the WHO guideline threshold “eliminated most of the deleterious associations of poor sleep with mortality”.

The findings lend weight to efforts to target both physical activity and sleep quality in a bid to improve health.