sleep time

And though getting enough quality sleep is important to brain health in midlife and beyond, the researchers said that when forced to choose between minutes spent sleeping and minutes spent exercising, reducing sleep time to spend more time moving resulted in better brain function.

"Screen time at bedtime displaces sleep time, which is essential for health and development in young adolescents," Nagata said.

When parsing baseline sleep data, the researchers found "consistent associations" between people's perceived stress scores and factors such as total sleep time, resting heart rate and heart rate variability, and respiratory rate.

"The fact that reindeer sleep the same amount during winter and summer implies that they must have other strategies to cope with limited sleep time during the arctic summer," says Furrer.

In one phase, they were asked to maintain their adequate sleep; in the other, they were asked to delay their bedtime for an hour and a half, shortening their total sleep time to around six hours.