New York, May 22 (IANS): Exercise not only helps in promoting strength and endurance but also improves the quality of your sleep at night, say researchers.

In a new study, the researchers from Pennsylvania State University, US observed that teenagers who work out during the day tend to sleep longer than those who don't exercise at all.

"Adolescence is a critical period to obtain adequate sleep, as sleep can affect cognitive and classroom performance, stress, and eating behaviours," said Lindsay Master, data scientist at Pennsylvania State University, US.

"Our research suggests that encouraging adolescents to spend more time exercising during the day may help their sleep health later that night," Master added.

The study's findings, published in Scientific Reports journal, showed that the teenagers, who did an extra hour of workout during the day, fell asleep 18 minutes earlier, 10 minutes longer and had about one percent greater sleep experience at night.

Moreover, the study also found that the teenagers, who slept for more minutes during the day, couldn't have an adequate sleep at night.

"You can think of these relationships between physical activity and sleep almost like a teeter totter," noted Orfeu Buxton, Professor at Penn State.

"When you're getting more steps, essentially, your sleep begins earlier, expands in duration, and is more efficient. Whereas if you're spending more time sedentary, it's like sitting on your sleep health: sleep length and quality goes down," Buxton asserted.

The researchers specified that the beneficial effects of exercise and sleep go together.

"...if we can encourage people to engage in more physical activity and better sleep health behaviours on a more regular basis, it could improve their health over time," Buxton affirmed.

For the study, the researchers used data of 417 US teenagers. The participants wore accelerometers on their wrists and hips to measure sleep and physical activity for one week.

"One of the strengths of this study was using the devices to get precise measurements about sleep and activity instead of asking participants about their own behaviour, which can sometimes be skewed," Master pointed out.

"The hip device measured activity during the day, and the wrist device measured what time the participants fell asleep and woke up, and also how efficiently they slept, which means how often they were sleeping versus tossing and turning," he noted.