Getting the blues when you least expect it is not an uncommon phenomenon in the fall. Psychiatrists even have a word for this mental condition -- seasonal affective disorder -- for those who suffer repeat bouts of depression when the mercury falls and sunlight hours dwindle, putting a severe dampener on their spirits.
Doctors believe such sudden mood swings are linked to the decreasing amount of sunlight during the day. "The human brain adjusts the biological rhythm of your body according to the amount of light," said Son Sang-joon, a psychiatrist at Aju University Hospital.
"Light is sensed by the optic nerve, and this affects the secretion of hormones such as melatonin and serotonin. Some people may become depressed, especially in the fall, because they lack enough serotonin, the hormone that helps keep us psychologically well-balanced."
One of the ways of dealing with this is to try and spend more time in the sun. "Exposing yourself to sunlight for more than 30 minutes a day ramps up the body's production of vitamin D, which stimulates the secretion of serotonin in the brain. It also helps to brighten the lights in your home or sit close to the window," Son said.
Other treatments include taking daily walks for at least 30 minutes at a time, eating more fresh fruit and vegetables, and taking nutritional supplements like vitamins.
Many Koreans believe women experience more mood swings in the spring and men in the fall, but this is a common misconception that is not medically proven.
"Seasonal affective disorder is more common among women than men," Son said. "This is because women tend to be more sensitive to their surroundings."
Women in their 40s and 50s who spend a lot of time by themselves are especially vulnerable to the seasonal blues, he said.