A new study published on February 26, 2025, in Proceedings of the Royal Society B challenges the widely held belief that modern, industrial societies are suffering from a sleep epidemic. Instead, researchers David Ryan Samson and Leela McKinnon suggest that people in industrialized nations are actually sleeping longer and more efficiently than those in small-scale, non-industrial societies—though at a cost to their circadian health.
Breaking the “Sleep Epidemic” Myth
For years, experts have warned of a growing sleep crisis fueled by long work hours, constant screen exposure, and modern stressors. In fact, the Centers for Disease Control and Prevention (CDC) has even declared sleep-related problems a public health epidemic. However, the new research paints a different picture.
Analyzing data from 54 global populations (including 5,101 participants) using wrist-worn actigraphy and polysomnography—the gold standard for sleep measurement—the researchers found that individuals in industrialized societies sleep about 45 minutes longer and with higher efficiency than their counterparts in small-scale, non-industrial communities.
“Rather than industrialized societies suffering from severe sleep loss, our findings suggest that modern lifestyles may actually promote longer and higher-quality sleep,” the authors write.
This finding contradicts the “sleep restriction epidemic hypothesis,” which argues that modern labor demands and technology have shortened sleep duration. Instead, the study suggests that industrial societies provide more stable, comfortable, and safe sleeping environments, which may enhance sleep quality.
Circadian Mismatch: The Hidden Cost of Industrialization
While industrial societies seem to have the upper hand in sleep duration and efficiency, they suffer in another crucial aspect: circadian function.
The researchers tested the “circadian mismatch hypothesis,” which suggests that modern environments—characterized by artificial lighting, temperature control, and reduced exposure to natural light—disrupt the body’s internal clock. Using an actigraphy-derived circadian function index (CFI), they found that people in non-industrial societies had significantly stronger circadian rhythms than those in industrialized settings.
Why does this matter? Circadian misalignment has been linked to a range of health issues, including metabolic disorders, cardiovascular disease, depression, and even increased cancer risk. The study suggests that while people in industrialized societies sleep more, they do so at the cost of weaker circadian function, which could have long-term health consequences.
Rethinking Sleep Health: Quality vs. Circadian Alignment
The study’s findings suggest that the real issue isn’t necessarily sleep duration, but how well our sleep aligns with our natural circadian rhythms. The researchers argue that interventions should focus not just on increasing sleep time but also on improving chronohygiene—a term for lifestyle habits that support healthy circadian function.
Some potential solutions include:
- Prioritizing natural light exposure during the day
- Reducing artificial light (especially blue light) in the evening
- Maintaining a consistent sleep schedule
- Aligning work and school schedules more closely with natural circadian rhythms
The Bigger Picture: Evolutionary Insights into Human Sleep
The research also provides an intriguing evolutionary perspective on human sleep. Hunter-gatherer societies like the Hadza of Tanzania and the San of Namibia typically sleep 5.5 to 6.5 hours per night, significantly shorter than the 7 to 9 hours recommended by modern sleep experts. This suggests that human sleep duration may not be biologically fixed, but rather shaped by environmental and cultural factors over time.
“Our study underscores that human sleep is dynamic and adaptable,” the researchers conclude. “Modern societies may have extended sleep duration, but they have also disrupted the very rhythms that regulate it.”
As sleep science evolves, this research encourages a shift in focus: from simply getting more sleep to ensuring our sleep is properly aligned with our body’s natural rhythms.
Research Study Source
Samson, D.R., & McKinnon, L. (February 26, 2025). Are humans facing a sleep epidemic or enlightenment? Large-scale, industrial societies exhibit long, efficient sleep yet weak circadian function. Proceedings of the Royal Society B. https://doi.org/10.1098/rspb.2024.2319
Disclaimer:
This article is a summary and interpretation of the research study “Are humans facing a sleep epidemic or enlightenment? Large-scale, industrial societies exhibit long, efficient sleep yet weak circadian function” by David Ryan Samson and Leela McKinnon, published in Proceedings of the Royal Society B on February 26, 2025. The content is intended for informational and educational purposes only and does not constitute medical, scientific, or professional advice.
While every effort has been made to accurately represent the study’s findings, readers should refer to the original publication for detailed methodologies, data interpretations, and conclusions. Any health-related recommendations mentioned are general in nature and should not replace consultation with qualified healthcare or sleep professionals.
The views expressed in this summary do not necessarily reflect those of the study authors, journal publishers, or affiliated institutions.
