The May blues are a period of low mood, fatigue, and lack of motivation that strikes in late spring, often catching people off guard during a season that’s supposed to feel hopeful. Unlike winter seasonal depression, which most people have heard of, the May blues don’t fit neatly into one clinical diagnosis. They’re driven by a mix of biological shifts, post-stress letdowns, and even allergic inflammation that converge during this specific window of the year.
Why Spring Can Feel Worse Than Winter
Most people assume depression peaks in the dark, cold months. The data tells a different story. Suicide rates are actually highest in April, May, and June, running two to three times higher than in December, when rates are lowest. As Adam Kaplin, a psychiatrist at Johns Hopkins, has explained, people who spent the winter depressed may emerge in spring still feeling dark and sad, but now with enough energy and motivation to act on those feelings. Spring also forces a painful contrast: the world is full of rebirth and social activity, and people struggling with low mood feel even more isolated by comparison.
This spring peak in distress is more pronounced at higher latitudes, where seasonal differences in daylight are more dramatic. Closer to the equator, where day length stays relatively stable year-round, the effect fades.
The Japanese Concept of “May Sickness”
Japan has a specific term for this phenomenon: gogatsu-byō, or May sickness. It originally described college freshmen who crashed emotionally after surviving the brutal entrance exam season that runs from February through March. Students would power through months of intense studying, feel a rush of excitement starting their new lives in April, and then hit a wall in May once the novelty wore off. The result was apathy so severe that some students stopped attending classes entirely.
The concept has since expanded beyond students. New employees in Japan, who also start their jobs in April, follow the same pattern. They spend their first month busy with orientation, new social networks, and the thrill of a fresh start. Once that honeymoon period ends, the exhaustion and disorientation of adjusting to a new environment catches up with them. May sickness is now understood as a post-stress crash: the body and mind finally registering the toll of months of pressure once the immediate demands are gone.
Biology Behind the Slump
Several biological mechanisms work together to destabilize mood in spring. The most significant involves your brain’s internal clock. As daylight hours increase rapidly in April and May, your circadian rhythm has to recalibrate. Light is the strongest signal that sets your internal clock, and that clock directly controls the production of serotonin (which regulates mood) and melatonin (which regulates sleep). During this transition, the systems that produce these chemicals can fall out of sync, leaving you simultaneously wired and exhausted.
Research from the National Institutes of Health shows that the length of the day persistently reshapes how serotonin-producing neurons behave, with melatonin acting as the go-between. When daylight shifts quickly, the adjustment isn’t instant. People with already-disrupted mood chemistry may be especially slow to adapt, which helps explain why spring is a vulnerable period for those with depression or anxiety.
Vitamin D levels also play a role, though not in the way you might expect. After a full winter of reduced sun exposure, many people enter spring with depleted vitamin D stores. Deficiency is defined as blood levels below 12 ng/mL, and insufficiency covers the range up to 30 ng/mL. Observational studies have linked low vitamin D to depression, and while supplementation studies have produced mixed results, the deficiency itself can contribute to the fatigue and low energy people feel in May before their levels have had time to recover.
Allergies and Mood Are Connected
One of the less obvious drivers of the May blues is pollen. Tree pollen peaks in spring, and it doesn’t just cause sneezing. When your body mounts an allergic response, it releases inflammatory signals called cytokines. Those same inflammatory molecules have been shown to worsen mood even in otherwise healthy people. In one study, people who reported mood worsening during high pollen counts were 1.68 times more likely to meet criteria for non-winter seasonal depression. The chances of depression were 42% higher in people with nasal inflammation (both allergic and non-allergic) compared to those without.
This connection between pollen and mood may help explain one of the more puzzling patterns in mental health: the spring peak in suicides coincides almost exactly with the spring peak in tree pollen across continents and hemispheres. Researchers have proposed that seasonal allergens create a “triple vulnerability” in people already predisposed to both allergy and depression. More than 50 million Americans experience seasonal allergies each year, putting a significant portion of the population at higher risk for mood disruption every spring.
How Long It Typically Lasts
For most people, the May blues are self-limiting. The Japanese concept of gogatsu-byō implies a timeline of weeks, not months. Once your body adjusts to the new season, your social routines stabilize, and the post-stress letdown passes, energy and motivation typically return. A rough guideline: if symptoms are clearly tied to the seasonal transition and begin to lift within a few weeks, you’re likely dealing with a normal adjustment period.
Formally diagnosed summer-pattern seasonal affective disorder is quite rare, affecting roughly 0.57% of the population globally, compared to about 5% for the winter pattern. But a broader category of “subsyndromal” seasonal depression, where symptoms are real but don’t meet the full diagnostic threshold, affects closer to 9% of people. If low mood, sleep disruption, or loss of interest persists beyond a few weeks and starts interfering with work or relationships, that’s a sign something more than a passing seasonal adjustment is happening.
What Helps
The most effective strategies target the specific mechanisms behind the May blues. Regular physical activity is consistently one of the strongest interventions for seasonal mood changes. It boosts serotonin, helps regulate your sleep-wake cycle, and counteracts the inertia that makes the May blues feel so heavy. Even moderate daily exercise, like a 30-minute walk outside, addresses multiple causes at once by combining movement with natural light exposure.
Sleep regulation matters more than most people realize during this transition. As daylight shifts, your sleep schedule can drift without you noticing. Setting consistent wake-up and bedtime anchors your circadian rhythm and helps your brain adjust to the new photoperiod faster. Resist the urge to nap or oversleep on weekends, which can make the adjustment harder.
Cognitive behavioral therapy adapted for seasonal depression focuses on two things: replacing negative seasonal thoughts with more realistic ones, and scheduling activities that re-engage you with life rather than letting you withdraw. Even without formal therapy, the principle is useful. The apathy of the May blues makes you want to cancel plans and stay home. Deliberately scheduling one enjoyable or social activity per day works against that pull.
If allergies are part of the picture, treating them aggressively may do more for your mood than you’d expect. Reducing the inflammatory load from pollen exposure can lower the cytokine levels that contribute to depressive symptoms. Managing allergies isn’t just about comfort; it’s a mood intervention.
For people coming out of winter with low vitamin D, spending more time outdoors in spring serves double duty. It helps rebuild vitamin D stores and provides the bright light exposure that recalibrates your circadian rhythm. On overcast days or for people in northern latitudes, a 10,000-lux light box used for 30 to 45 minutes in the morning can substitute for sunlight, though this is more commonly associated with winter depression treatment.