Researchers from Charité Medical University in Berlin observed a seasonal shift in sleep patterns, with people spending more time in REM sleep during the winter months. The findings appeared in Frontiers in Neuroscience, a journal that focuses on brain and sleep research.
In earlier work, participants often reported longer sleep durations in winter. The new study built on that by using objective measurements rather than self-reporting. Sleep duration and quality were tracked through polysomnography, a comprehensive recording of brain activity, eye movements, muscle activity, heart rate, and breathing. The data provided a precise picture of how winter affects sleep architecture. — Charité researchers; Frontiers in Neuroscience.
Part of the investigation focused on individuals experiencing sleep disturbances. Across data drawn from 188 patients who underwent polysomnography at Hedwig’s Hospital, insomnia was found to be diagnosed more frequently as the year drew to a close. The pattern suggests a seasonal influence on sleep complaints, even in a clinical setting. — Hedwig’s Hospital team; Frontiers in Neuroscience.
Despite living in an urban environment with relatively low natural light exposure and significant light pollution, the patients exhibited clear seasonal rhythms in their sleep. In winter, total sleep time remained about the same, but REM sleep increased by roughly half an hour compared with summer. This rise in REM aligns with known links between REM, circadian timing, and the environmental light cycle. The researchers point to light as a key regulator of these seasonal shifts. — Charité and partners; Frontiers in Neuroscience.
The researchers emphasize the need to verify these seasonal patterns in healthy individuals who do not report sleep problems. They propose that the observed effects could be amplified in people without underlying sleep disorders, potentially making winter a more distinctive period for REM-dominated sleep in the broader population. Further studies are encouraged to explore whether these patterns persist across different climates and age groups, and to determine the practical implications for sleep health and daily functioning. — Charité scientists; Frontiers in Neuroscience.