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New research suggests that we may need more sleep during the colder months. Whether we're early risers or late sleepers, our biological clocks are set by the sun. That's why we might need to adjust our habits, including our work schedules, to suit the season.
New research suggests that we may need more sleep during the colder months. Whether we're early risers or late sleepers, our biological clocks are set by the sun. That's why we might need to adjust our habits, including our work schedules, to suit the season.
Research from the Clinic for Sleep and Chronomedicine at St. Hedwig's Hospital in Germany suggests that, even in an urban population with disrupted sleep, people experience longer REM sleep in winter than in summer, and less deep sleep in the fall.
The findings, published in the journal Frontiers in Neuroscience, suggest that seasonality is related to the quality of sleep in humans. REM sleep is the period of very deep sleep during which we make rapid eye movements. It is also the period during which most dreams occur.
To carry out their research, the scientists studied 188 patients who have difficulty sleeping, but who do not use sleeping pills. They slept naturally in a special laboratory, where they had no alarm clock. Their sleep quality and duration were monitored over the course of a year. Although total sleep time appeared to be about an hour longer in winter than in 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 related to the circadian clock, which is affected by changes in light.
"Seasonality is ubiquitous in any living being on this planet. 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," explains corresponding author Dr Dieter Kunz, in a statement.
Although the team acknowledged that these results would need to be validated in a population without sleep disorders, seasonal changes may be even more significant in a healthy population. "In general, societies need to adjust sleep habits including length and timing to season, or adjust school and working schedules to seasonal sleep needs," concludes Dr Kunz.
