Why does spring make you feel tired?
If you have found yourself fighting off yawns despite getting a full night’s sleep, you are not alone. As the weather warms and sunlight stretches into the early evenings, many begin to feel unusually drowsy or sluggish.
In Korea, this familiar seasonal fatigue is commonly called "chun-gon-jeung," which literally translates to "spring tiredness."
Doctors stress that this isn’t a disease but a physiological adjustment period. As winter transitions into spring, the body is suddenly asked to recalibrate its internal rhythms.
Still, the fact that spring fatigue isn’t an official medical condition doesn’t mean the tiredness is imagined. Headaches, mild dizziness, digestive discomfort and a waning appetite can accompany the mental slowdown, and when these symptoms persist, it becomes harder to push through the workday as usual.
Warmer temperatures encourage more outdoor movement, daylight expands rapidly, and hormonal cycles shift in response to earlier sunrise. All of this requires energy.
“It’s a temporary fatigue response caused by changes in biological rhythms and living environments,” said Hwang Sun-wook, a family medicine professor at Incheon St. Mary’s Hospital, who noted that most people improve naturally once their routines stabilize.
Much of spring fatigue can be traced back to how sunlight affects the body’s internal clock. Humans operate on a roughly 24-hour cycle regulated by the suprachiasmatic nucleus in the brain, which acts as the body’s central timekeeper. When light enters the eyes, this biological clock adjusts everything from sleep and alertness to hormone release and body temperature.
In spring, those signals shift. As dawn comes earlier and dusk arrives later, melatonin, the hormone that promotes sleep, is released at different times. This results in a temporary mismatch between your natural sleep-wake rhythm that can leave you feeling groggy during the day.
Spring tiredness can also reflect low oxygen transport in the blood, a sign that the body may be running short on iron. Red blood cells deliver oxygen to the body using hemoglobin, which relies on iron to function.
Even if you are otherwise eating well and staying hydrated, insufficient iron prevents cells from receiving the oxygen they need, causing them to work less efficiently and leaving you feeling drained.
Experts warn that fatigue that lingers for several weeks, worsens, or comes with symptoms like weight loss, night sweats or fever may point to an underlying condition such as thyroid dysfunction, anemia or sleep apnea.
“It isn’t advisable to dismiss all spring fatigue as chun-gon-jeung,” Hwang said. “If tiredness persists for three to four weeks despite rest, a medical evaluation is necessary.”
Experts say the solution begins with restoring balance to the internal clock. A consistent sleep schedule — going to bed and waking up at the same time every day — helps the body resynchronize more smoothly.
Morning sunlight is especially helpful because it provides a strong cue to reset the circadian rhythm. Regular physical activity also supports the adjustment, but leaning on caffeine to “power through” tends to backfire by disrupting nighttime sleep and intensifying fatigue the next day.
Certain foods can also help replenish iron naturally.
Shellfish, including oysters, mussels and clams, contain highly absorbable heme iron, the type the body uses most effectively to build hemoglobin. Because heme iron requires no conversion inside the body, eating shellfish can quickly improve oxygen transport and reduce fatigue.
These foods also supply vitamin B12 and zinc, both essential for red blood cell formation and immune function. Oysters, packed with minerals, are especially valued for boosting low energy and supporting overall vitality.
Beef is another strong source of heme iron. Lean cuts offer not only iron but also protein and B vitamins, which the body relies on to produce red blood cells and maintain steady energy metabolism.
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