For people who wish they could work out in the evening but don’t because they worry about its effect on their sleep, there’s good news.
Researchers at Charles Sturt University in Bathurst, Australia, discovered that 30 minutes of high-intensity interval training exercise between 7 p.m. and 9 p.m. didn’t cause any sleep problems. And, as an added bonus, evening and afternoon exercise sessions reduced the hunger hormone, ghrelin.
“With growing demands on our time, many middle-aged adults are finding time to engage in exercise increasingly difficult,” lead author Penelope Larsen said in a university news release. “For many, even the thought of fitting exercise in after a busy day at work can be as tiring as it is unappetizing. The commonly held belief that high-intensity exercise should be avoided in the early evening due to its effect on sleep only serves to act as another barrier to exercise at this time.”
In the study, 11 middle-aged men completed three experiments with exercise at different times of day — morning (between 6 a.m. and 7 a.m.), afternoon (between 2 p.m. and 4 p.m.) and evening (between 7 p.m. and 9 p.m.).
They cycled six one-minute sprints interspersed with four-minute rests. Researchers collected blood both before and after the exercise to measure appetite-related hormones. They also assessed participants’ sleep.
In addition to the findings about sleep and appetite, researchers discovered that participants put out more power during the sprints during the afternoon and evening sessions than in the morning.
“In the future, we hope to conduct similar studies recruiting women to determine whether sleep and appetite responses may be different depending on gender,” Larsen said.