On its website, MyShake suggests opening the app every month or so to keep it “fresh and ready to receive alerts. Not using the app for a prolonged period might cause the app to be put into deep sleep.”

"It is not just the duration of deep sleep stages but also an intact structure of our sleep."

“It is not just the duration of deep sleep stages but also an intact structure of our sleep,” Mittermaier said.

The study found that the women who spent more time in deep sleep -- the third and deepest stage of sleep -- tended to have lower blood pressure than women who spent less time in this stage.

Still, Knutson said the results of the current study could guide future work that explores the underlying mechanisms that may be making deep sleep in particular more valuable for women.