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hubie [soylentnews.org] writes:

Although seasonality in animal sleep is well known, we've assumed humans are different [frontiersin.org]:

Whether we're night owls or morning larks, our body clocks are set by the sun. Theoretically, changing day length and light exposure over the course of the year could affect the duration and quality of our sleep. But figuring out how this applies in practice is difficult. Although studies where people assess their own sleep have suggested an increase in sleep duration during winter, objective measures are needed to determine how exactly the seasons affect sleep. Scientists studying sleep difficulties have now published data in Frontiers in Neuroscience [frontiersin.org] that shows that, even in an urban population experiencing disrupted sleep, humans experience longer REM sleep in winter than summer and less deep sleep in autumn.

"Possibly one of the most precious achievements in human evolution is an almost invisibility of seasonality on the behavioral level," said Dr Dieter Kunz, corresponding author of the study, based at the Clinic of Sleep & Chronomedicine at the St Hedwig Hospital, Berlin. "In our study we show that human sleep architecture varies substantially across seasons in an adult population living in an urban environment."

[...] 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, the scientists found subtle but striking changes across the seasons. Although total sleep time appeared to be about an hour longer in the winter than the summer, this result was not statistically significant. However, REM sleep was 30 minutes longer in the 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 which experiences no sleep difficulties, the seasonal changes may be even greater in a healthy population.

[...] "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."

Journal Reference:
Aileen Seidler, Katy Sarah Weihrich, Frederik Bes, et al., Seasonality of human sleep: Polysomnographic data of a neuropsychiatric sleep clinic, Front. Neurosci., 17, 2023. DOI: https://doi.org/10.3389/fnins.2023.1105233 [doi.org]

Original Submission