23 March 2026
Jasmin Cohen
With the first warm days, it’s not just nature that changes. The human body also responds to the shift in seasons. Many people report feeling tired in spring, experiencing irritated eyes, or having a runny nose. The term “spring fatigue” is often used, although it is not scientifically defined. Still, studies show that various biological processes in the body do change with the seasons — from hormonal adjustments and shifts in the sleep–wake cycle to measurable fluctuations in the immune system.
Spring is, above all, a phase of transition for the body.
Many people show measurable responses to seasonal changes. Modern studies suggest that key processes in the body vary throughout the year.
A large UK study involving nearly 300,000 participants found that several health markers related to the immune system vary not only throughout the day but also across seasons. These included inflammatory markers, white blood cells, and antibody levels.¹ Researchers believe these changes are part of a circadian rhythm — a biological adaptation to recurring environmental factors such as daylight, temperature, or vitamin D levels.¹
Other studies show that seasonal changes can even be observed at the genetic level. Thousands of genes in immune cells, for example, have been identified whose activity varies throughout the year.² These findings suggest that the immune system dynamically adapts to environmental changes such as the onset of spring.
The circadian rhythm — our internal biological clock — regulates many essential processes, including:
sleep and wakefulness
hormone production
metabolism
immune cell activity
Research shows that both innate and adaptive immune responses are influenced by circadian rhythms.³ For example, immune activity changes throughout the day, and the number of certain immune cells in the blood fluctuates accordingly.³
Daylight plays a key role in seasonal transitions. As days become longer in spring, the body adjusts to new light and activity patterns. This adjustment can temporarily affect sleep quality, energy levels, and immune processes.
At the same time, spring marks the start of pollen season. For many people, exposure to pollen has little impact. However, in individuals with allergies, the immune system reacts differently.
In allergic reactions, the immune system mistakenly identifies harmless substances as threats. As a result, immune cells are activated and inflammatory substances such as histamine are released.
This can lead to typical symptoms such as:
sneezing
itchy or watery eyes
a blocked or runny nose
fatigue or difficulty concentrating
Recent studies also show that certain inflammatory markers in the body can measurably change during pollen season.⁴
Because symptoms like fatigue or irritated airways often occur alongside seasonal changes, they are not always immediately recognized as allergies.
Typical signs of a seasonal allergy include:
symptoms occur at the same time each year
symptoms persist for several weeks
itchy eyes or nose are prominent
fever is usually absent
Allergies can develop or change over time, which means it is not uncommon for symptoms to appear for the first time in adulthood.
If symptoms occur regularly in spring or persist over time, an allergy test can help identify possible triggers.
Such a test can help to:
identify allergens
better understand symptoms
plan targeted measures for everyday life
With the MavieMe allergy test, you can conveniently test for 98 allergens from home and gain insights into your individual sensitivities.
Not all allergic reactions are the same. Medical evaluation is particularly recommended if:
symptoms are severe
symptoms persist over time
breathing difficulties occur
an allergy is suspected for the first time
Medical consultation helps to properly assess symptoms and discuss possible treatment options.
Medical facilities such as Mavie Med offer specialized diagnostics and individualized care. Mavie Telemed enables a simple online consultation with general practitioners via video or audio call — from the comfort of your home.
The beginning of spring brings many positive changes, such as longer days and warmer temperatures. At the same time, the body needs to adapt to new environmental conditions.
Increased daylight, changes in sleep rhythms, and the start of pollen season all influence various biological systems — especially the immune system.
If symptoms occur or recur regularly, it can be helpful to take a closer look at the underlying causes.
Sources
1. Wyse CA et al. Seasonal and daytime variation in multiple immune parameters in humans. iScience (2021). https://www.cell.com/iscience/fulltext/S2589-0042(21)00223-6
2. Dopico XC et al. Widespread seasonal gene expression reveals annual rhythms in human immunity. Nature Communications 2020 analysis continuation). https://www.probiologists.com/article/i-see-the-light-the-role-of-seasonal-photo-period-in-the-development-of-immune-regulation-a-potential-explanation-for-the-latitude-gradient-of-autoimmunity-and-allergy
3. Waggoner SN et al. Circadian rhythms in immunity. Current Opinion in Immunology (2020). https://pmc.ncbi.nlm.nih.gov/articles/PMC7357859
4. Shen J et al. Seasonal proteomic variations in allergic rhinitis. Frontiers / biomedical study (2025). https://pmc.ncbi.nlm.nih.gov/articles/PMC12083496
5. Wang C et al. The circadian immune system. Science Immunology (2022). https://www.science.org/doi/10.1126/sciimmunol.abm2465
