Exercising too close to bedtime may lead to disruptive sleep, a landmark Australian study has found.

Researchers at Monash University in Melbourne tracked more than 14,000 people over a year and found high-impact exercise at night keeps the body and brain alert before bedtime.

The study, published in the journal Nature Communications, showed that exercising four hours or less before bedtime was linked to falling asleep later, experiencing less and worse quality sleep and a higher heart rate.

It was the first and largest study to identify this.

The research involved an international sample of 14,689 people wearing a multi-sensor biometric device to record exercise, sleep and cardiovascular data over one year.

The results were adjusted for gender, age, weekday, season, general fitness and the prior night’s sleep.

Researchers found high-strain activities, such as HIIT workouts (high-intensity interval training), football and rugby games or a long run, had the biggest impact on sleep patterns.

They lead to sustained increases in breathing rate, core body temperature, heart rate and mental alertness.

First author Dr Josh Leota, from the Monash University School of Psychological Sciences, said fitness enthusiasts would be better off picking lower intensity pursuits closer to bedtime.

“If exercising within a four-hour window of bedtime, people could choose brief low intensity exercises, such as a light jog or swim, to minimise sleep disruption and allow the body to wind down,” he said.