Females sleep less, wake more often, and experience less restorative sleep than males, according to a new study on mice. The findings highlight critical biological differences in sleep patterns and suggest the need for more inclusive research practices in biomedical studies.
Published in Scientific Reports | Estimated reading time: 6 minutes
Understanding the Sleep Gap
A recent study by researchers at the University of Colorado Boulder found that female mice, on average, sleep about an hour less per day than their male counterparts. The disparity lies in non-rapid eye movement (NREM) sleep, a restorative phase when the body undergoes repair. Female mice also experienced shorter and more fragmented sleep bouts, likely reflecting evolutionary adaptations for heightened environmental sensitivity.
“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 and senior author of the study. “Our results suggest that biological factors may play a more substantial role in driving these sleep differences than previously recognized.”
These findings have broad implications, particularly for biomedical research, where female representation has historically been limited. For instance, a simulated analysis within the study demonstrated that failing to account for sex differences can lead to flawed interpretations of sleep-related data.
Sex Bias in Sleep Research
Mice have long been used as models for understanding human sleep and testing sleep-related treatments. However, as Rowe pointed out, sex differences in sleep behavior are often overlooked, skewing results. The National Institutes of Health took a step toward addressing this issue in 2016 by requiring researchers to account for sex as a biological variable in grant proposals, yet challenges remain.
“When females are underrepresented, drugs that work best for them may seem ineffective, or side effects that hit hardest may go unnoticed,” Rowe explained. This oversight could partially explain the decades-long timeline for translating animal research into effective human treatments.
Broader Implications
The study underscores the importance of analyzing male and female data separately in preclinical research. “The most surprising finding here isn’t that male and female mice sleep differently. It’s that no one has thoroughly shown this until now,” Rowe added.
By ensuring equal representation in study samples, researchers can improve the accuracy of biomedical research and pave the way for more effective, inclusive treatments.
Glossary
- Non-Rapid Eye Movement (NREM) Sleep: A deep, restorative stage of sleep crucial for physical repair.
- Polyphasic Sleep: A sleep pattern involving multiple short bouts of sleep and wakefulness.
- Piezoelectric Sensors: Devices that detect movement through changes in electrical charge, used in this study to measure sleep behavior.
- Sex Bias: The underrepresentation or unequal treatment of one sex in scientific research.
- Translational Research: The process of applying findings from basic research to develop practical applications, such as medical treatments.
Interactive Quiz
What is the main finding of the study?
Females sleep less, wake more often, and have more fragmented sleep than males.
What type of sleep is most impacted in females?
Non-Rapid Eye Movement (NREM) sleep.
Why is female representation critical in sleep studies?
Underrepresentation can lead to flawed interpretations of data and overlooked treatments or side effects.
Which organization mandates accounting for sex in animal studies?
The National Institutes of Health (NIH).
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