Humans may need more sleep during the winter, according to a study that will be some comfort to those who struggle to get out of bed during the colder months.
A team of scientists led by Aileen Seidler at the Charite Medical University of Berlin found that humans experience longer REM (rapid eye movement) sleep in winter than in summer.
The study’s participants were in an urban environment with high levels of light pollution and low levels of natural light – factors that disrupt the body’s circadian clock.
However, their REM sleep was found to be 30 minutes longer in the winter than in summer.
The scientists said that the results need to be replicated in people with no sleep difficulties, but the seasonal differences could be even greater in a population of healthy sleepers.
The study said: “For many people, the time to wake up is more strongly controlled by their employer’s business hours or school times than by their internal clock.
“Adjustment of sleep schedule can, therefore, only be controlled by choosing the time to go to bed.
“Nevertheless, keeping to the same time is widely recommended and often enforced religiously on children.
“Our findings suggest that improvements can be made by accounting for the increased sleep need in winter, by going to bed earlier.”
Read more:
Early bird or night owl?
Phase of the moon may be to blam for your sleep struggles
REM sleep plays an important role in dreaming, memory, emotional processing, and healthy brain development.
Normal sleep starts with three stages of non-REM sleep, followed by a short period of REM sleep.
But, as our body clocks are set by the sun, the changing length of days and light exposure over the course of a year could affect the duration and quality of sleep.
Dr Dieter Kunz, corresponding author of the study, based at the Clinic Of Sleep And Chronomedicine at the St Hedwig Hospital in Germany, said: “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.
“In general, societies need to adjust sleep habits including length and timing to season, or adjust school and working schedules to seasonal sleep needs.”
The findings are published in the Frontiers in Neuroscience journal.
