Summary of Do Humans Hibernate? No, but We Still Need More Winter Sleep:
New research suggests that humans experience longer REM sleep in winter compared to summer, and less deep sleep in autumn. The study, which was published in the journal Frontiers in Neuroscience, analyzed people in urban areas who experience disrupted sleep. Researchers analyzed patients undergoing sleep studies and found that most diagnoses showed no seasonal pattern but insomnia was more commonly diagnosed towards the end of the year. The increase in REM sleep in winter is thought to be due to its direct link to the circadian clock, which is affected by changing light. The authors caution that the study needs to be replicated in a large cohort of healthy subjects to validate the findings.
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Seasonal Changes in Sleep: Understanding the Link Between Winter and More REM Sleep
As humans, we all know how important it is to get enough sleep. But did you know that the seasons can affect the duration and quality of our sleep? According to new research published in the journal Frontiers in Neuroscience, humans have longer REM sleep in winter compared to summer, and less deep sleep in autumn. This finding is particularly interesting because it shows that seasonal changes affect sleep, even in an urban population experiencing disrupted sleep.
Studying Sleep
To understand how the seasons influence sleep, a team of scientists led by Ms. Aileen Seidler in Dr. Dieter Kunz’s working group at the Charité Medical University of Berlin recruited 292 patients who had undergone sleep studies called polysomnographies at the St Hedwig Hospital. These studies are regularly carried out on patients who experience sleep-related difficulties in a special laboratory where the quality and type of sleep can be monitored as well as the length of sleep. Although the sleep disorders could potentially affect the results, this makes for study group evenly spread throughout the year, allowing for the investigation of month-to-month differences.
Winter Sees More REM Sleep
Even though the patients were based in an urban environment with low natural light exposure and high light pollution, which should affect any seasonality regulated by light, scientists found subtle but striking changes across the seasons. Although total sleep time appeared to be about an hour longer in winter than summer, this result was not statistically significant. However, REM sleep was 30 minutes longer in winter than in summer. REM sleep is known to be directly linked to the circadian clock, which is affected by changing light. Although the team acknowledged that these results would need to be validated in a population that experiences no sleep difficulties, the seasonal changes may be even greater in a healthy population.
Adapting to Seasonal Changes
Although most people’s waking time is currently largely out of their control, due to work or school schedules, society might benefit from accommodations that would allow humans to respond more effectively to these seasonal changes. In the meantime, going to sleep earlier in the winter might help accommodate human seasonality.
“Seasonality is ubiquitous in any living being on this planet,” said Kunz. “Even though we still perform unchanged, over the winter human physiology is down-regulated, with a sensation of ‘running-on-empty’ in February or March. In general, societies need to adjust sleep habits including length and timing to season, or adjust school and working schedules to seasonal sleep needs.”
Conclusion
Although the study needs to be replicated in a large cohort of healthy subjects, it shows that seasonal changes can affect our sleep patterns. Specifically, humans experience longer REM sleep in winter than summer and less deep sleep in autumn. While it may be difficult to adapt to these changes fully, understanding how they impact our sleep can lead to healthier and more restful sleep patterns, and ultimately better overall health.
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