TOKYO -- During winter, some experience health issues, along with thoughts like "I feel kind of depressed," "I'm sleepy even after a lot of sleep," "I gained weight from increased appetite," and so on. While easy to dismiss these as merely struggling with cold weather, an expert notes that "winter depression" could be to blame.

Also known as "winter blues," winter depression is a seasonal affective disorder that appears in the colder months, and is believed to be related to the shorter daylight hours. Reduced exposure to sunlight apparently affects the hormones that regulate sleep rhythms and neurotransmitters that stabilize the mind.

Symptoms of depression typically include weight loss due to decreased appetite and inability to sleep day or night even when trying to do so. However, the opposite is true for winter depression, with a marked increase in appetite and cravings for carbohydrates and sweets compared to normal, as well as longer sleeps at night, more sleepiness during the day and more napping and dozing.

Morning sun and daily rhythm

According to Dr. Ryota Osawa of Kokoromi Clinic, which runs psychosomatic medicine clinics mainly in Tokyo and adjacent Kanagawa Prefecture, it's important to be aware of both a proper daily rhythm and social stimulation through moderate contact with others to remedy winter depression.

As the first step toward an adequate daily rhythm, one should set their wake time as much as possible. Osawa said, "The key is to keep your wake-up time constant, and to limit the difference to about one hour at most, even on days off."

While preferable to get some sunlight upon waking, artificial light can also be effective, so simply turning on the lights in your room when you wake up is fine. Also recommended is to establish a daily rhythm with a routine such as taking a walk around the neighborhood or taking out the trash in the morning.

Exposure to light during the day causes the secretion of serotonin in the brain, which affects the autonomic nervous system and mental state. The serotonin secreted during the day stimulates the nighttime secretion of melatonin, a hormone which induces sleep.

Serotonin is synthesized from tryptophan, a protein found in meat, fish, dairy and soy products. Although it is a good idea to actively consume these foods, the average Japanese diet provides sufficient amounts of these without excessive intake. For this reason, Osawa said, "It's more important to eat regularly and in good balance." One option is to use apps supervised by dieticians that allow you to track your diet.

'Quality and quantity' important in interpersonal relationships

"Social stimulation" refers to interpersonal relationships, and the key concept is "not too much, not too little, and in moderation." Interacting with people in moderation is key, while balancing quality and quantity.

Osawa said, "If you pack your schedule with too many plans to meet with others, social stimulation can become too strong, and it can be painful to be alone all the time. It's critical to be aware of 'moderate stimulation' in one's daily life so as not to disrupt one's physical and mental balance through contact with others."

If your winter blues do not remedy even after reviewing your lifestyle, Osawa said, "People with mood swings tend to be more prone to winter depression. There is also a possibility of serious bipolar disorder as a cause of poor health, so please see a doctor if you're suffering from symptoms that interfere with your life."

(Japanese original by Hisako Sugita, Digital News Group)