As days grow longer and the first buds appear outdoors, many people complain each year of a recurring state of exhaustion: spring fatigue. Are they imagining it? Its existence cannot be scientifically proven, Swiss researchers reported in the Journal of Sleep Research.

According to a study of 418 participants, spring fatigue is more of a cultural than a biologically measurable phenomenon, write Christine Blume of the Center for Chronobiology at the University of Basel, Basel, Switzerland, and Albrecht Vorster, head of the Swiss Sleep House Bern, Department of Neurology, University Hospital Inselspital Bern, Bern, Switzerland. Their work was supported by the Swiss National Science Foundation and the German Society for Sleep Research and Sleep Medicine — a professional body for sleep researchers and clinicians in Germany. The authors, both of whom grew up in Germany, say this is the first study ever to address spring fatigue explicitly. In a representative survey from 2022, 22% of men and 39% of women reported being affected by it, Blume and Vorster wrote.

Perception Over Biology

To investigate this apparently widespread phenomenon scientifically and determine whether people are really more tired and more easily exhausted in spring than in other seasons, the two sleep researchers recruited 418 adults starting in April 2024 for an online survey; 80% of participants were women.

Through September 2025, Blume and Vorster contacted participants every 6 weeks, a total of nine times. Each time, respondents were asked to report how tired and exhausted they had felt during the previous 4 weeks. They were also asked about daytime sleepiness, any symptoms of insomnia, and their sleep quality. At the start of the study, almost 47% of participants said they suffered from spring fatigue.

However, an analysis of the data collected in the survey did not confirm that. “Repeated assessments over the course of a year showed no evidence of seasonal or monthly fluctuations in fatigue, sleepiness, insomnia symptoms, or sleep quality,” Blume and Vorster wrote. Only fatigue during daily activities decreased as day length increased. That decrease was independent of the rate of change in day length.

Cultural Labeling Effect

“In spring, the days lengthen rapidly. If spring fatigue were a genuine biological phenomenon, it should be particularly noticeable during this transitional phase, perhaps because the body needs to adapt,” Blume said in a statement from the University of Basel. The speed with which day length changes, however, did not appear to affect participants’ fatigue and exhaustion. 

“Overall, the results suggest that spring fatigue is not a true seasonal phenomenon,” the researchers wrote. The discrepancy between self-reports of this phenomenon and the stable longitudinal patterns suggests that spring fatigue is more of a cultural label and the result of cognitive perceptual biases than a genuine seasonal syndrome.

Because a well-established term exists, many people pay more attention to how tired they feel in spring and blame the season when they are exhausted. The phenomenon thus becomes a self-reinforcing explanation.

Fatigue that occurs in spring is likely experienced more intensely and remembered better than fatigue in other seasons, simply because there is a label for it, the researchers wrote.

Clock Change Fatigue

“We may also feel in spring that we should be more active and make the most of the good weather. If we then don’t manage to get going, expectations and subjective energy levels diverge,” Blume added. Attributing this to spring fatigue — or using it as an excuse — comes in handy: “It’s an explanation that’s completely accepted in society.”

However, the results cannot rule out that certain subgroups — such as people with hay fever or those with low vitamin D levels — may be more tired than usual at the end of winter or the start of spring.

The switch to summertime, which takes place in Europe on the last weekend in March, can also disrupt sleep and lead to increased fatigue (daylight saving time). But none of that explains the large number of people who reportedly suffer from spring fatigue.

Light, Exercise, and Sleep

In general, many people feel more tired and sleep somewhat more during the dark months. This is supported by earlier chronobiological research, and it also appears in the Swiss study participants’ responses. One reason may be that the biological night, which is governed by the internal clock, is somewhat longer in the winter months. “That also means we should actually feel more energeticwhen days get longer again,” Blume said.

The effect is especially notable in summer. “Many people generally sleep less in summer: Days are long, and you may meet friends in the evening and enjoy summer nights,” Blume said. Despite sleeping less, reported exhaustion did not increase — a finding confirmed in their study.

For those who lack energy in spring, Blume advises getting as much daylight as possible, exercising regularly, and getting sufficient sleep.

This story was translated from Medscape’s German edition.