The study, published in the journal Scientific Reports, showed that women sleep less, and wake up more often. They also get less restorative sleep than men. The findings based on experiments in mice shed new light on what may underlie sleep differences in men and women. "In humans, men and women exhibit distinct sleep patterns, often attributed to lifestyle factors and caregiving roles," said Rachel Rowe, assistant professor of integrative physiology at the University of Colorado at Boulder, US. "

Our results suggest that biological factors may play a more substantial role in driving these sleep differences than previously recognised," Rowe added. Sleep research has exploded in recent years, with thousands of animal studies exploring how insufficient sleep impacts the risk of diseases like diabetes, obesity, Alzheimer's, and immune disorders -- and how such diseases impact sleep. For the non-invasive study, the team used specialised cages lined with ultrasensitive movement sensors to assess the sleep patterns of 267 "C57BL/6J" mice. They found that males slept about 670 minutes total per 24-hour period, about an hour more than female mice.

That extra sleep was non-rapid Eye Movement (NREM) sleep -- the restorative sleep when the body works to repair itself. Female mice were found to have shorter bouts of sleep -- essentially, their sleep is more fragmented. The study saw similar sex differences in other animals, including fruit flies, rats, zebrafish, and birds. Rowe said biologically, "females are designed to be more sensitive to their environment and be aroused when they need to be because they are typically the ones who are caring for the young," Rowe said, noting that stress hormones like cortisol (which promotes wakefulness) and sex hormones also may play a role. The team hopes for more research to understand the underlying biological differences that can boost sleep treatment