As the days begin to get longer again, Dr. Christine Bloom’s phone rings frequently. That’s because journalists want to ask sleep researchers what spring fatigue is.
Up until now, she has always responded that no studies have investigated this phenomenon. “But I always felt that this was not enough,” says Bloom, a researcher at the University Psychiatric Clinic (UPK) and the Center for Chronobiology at the University of Basel. So she teamed up with Dr. Albrecht Forster, a sleep researcher at the University of Bern’s Inselspital, to conduct a study to find out whether people are actually more tired in the spring than at other times of the year. The result is Journal of Sleep Research.
“Spring fatigue” is rampant
The study was based on an online survey in which participants were contacted every six weeks for one year starting in April 2024, and researchers evaluated responses from 418 people. In the survey, participants stated how tired they felt over the past four weeks. We also asked about daytime sleepiness and sleep quality. The study was repeated covering different seasons.
At the beginning of the study, about half of the participants said they were suffering from spring fatigue.
This should have been clear from the evaluation of the survey data. ”
Christine Bloom, Research Leader
But that wasn’t the case.
Less fit than desired
“In spring, the days get longer rapidly. If spring fatigue is a genuine biological phenomenon, it should become evident during this transition period, for example because the body needs to adapt,” says the sleep researcher. However, the data showed that the rate of change in day length had no effect on participants’ fatigue. Similarly, no differences were found between individual months or seasons.
Researchers interpret the discrepancy between subjective perceptions and measured data as an indication that spring fatigue is a culturally influenced phenomenon rather than an actual seasonal syndrome. Since there is an established terminology for this, many people pay more attention to the feeling of fatigue they feel in the spring and interpret the symptoms of fatigue accordingly. Therefore, this phenomenon self-perpetuates itself many times over.
“In spring, we may feel the need to be more active and take advantage of the good weather. If we don’t feel like doing so, our expectations and subjective energy levels can be very different,” says the expert. It’s useful to explain or excuse this as spring fatigue. “That’s an explanation that’s completely accepted by society.”
Sunlight affects our body clock
In general, many people feel more tired and sleep a little more during the dark months of the year. This has been confirmed by chronobiological tests and is also reflected in the data provided by study participants. One reason for this may be that the biological night, controlled by our body clock, lasts a little longer during the winter. “But it also means we should actually become healthier as the days get longer again,” the scientist says.
As data analysis reveals, this is especially true in the summer. “At this time of year, many people generally sleep less. The days are longer and you may meet up with friends in the evening to enjoy the summer evenings,” says Christine Bloom. Even if you sleep less, you won’t feel more tired. This was also confirmed in research. Psychologists recommend those who feel lethargic in spring to get as much sunlight as possible, stay physically active and get enough sleep. And this year, for the first time, when the media inquires about spring fatigue, they will be able to refer to empirical data.
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Reference magazines:
Blume, C., & Vorster, A. (2026) No evidence for seasonal variation in symptoms of fatigue, sleepiness, and insomnia: Spring fatigue is a cultural phenomenon rather than a seasonal syndrome. sleep research journal. DOI: 10.1101/2025.09.27.678954.
