Reference; https://mbp-japan.com/jijico/articles/32459/
Modified and translated by CFJA
Doyo, the Seasonal Transition Period, Brings Large Temperature Swings — Proper Self-Care During Winter Doyo Is Important for Preventing Illness
2025 was the hottest summer on record.
It is often said that when the summer is extremely hot, the following winter tends to be cold. True to that saying, a severe cold wave began on Wednesday, January 21, 2026, affecting not only the Japanese archipelago but also North America.
In Eastern thought, the periods marking seasonal transitions are called Doyo.
Doyo refers to the 18 days preceding each of the four seasonal turning points: the beginning of spring, summer, autumn, and winter. These occur four times a year and are called Spring Doyo, Summer Doyo, Autumn Doyo, and Winter Doyo.
According to the 2026 calendar:
- Winter Doyo: the 18 days before the beginning of spring (February 4)
(January 16 – February 3) - Spring Doyo: the 18 days before the beginning of summer (May 5)
(April 17 – May 4) - Summer Doyo: the 18 days before the beginning of autumn (August 7)
(July 20 – August 6) - Autumn Doyo: the 18 days before the beginning of winter (November 7)
(October 20 – November 6)
In Eastern medicine, each season is associated with an organ that is considered to be most active:
spring with the liver, summer with the heart, autumn with the lungs, and winter with the kidneys.
During the Doyo periods, the spleen is thought to be particularly active.
From another perspective, these are also times when these organs are more vulnerable. If one overworks, eats poorly, or neglects proper self-care, the functions of these organs may decline more easily.
January 21, when the severe cold wave began, fell within the Winter Doyo period.
In fact, the cold had already intensified in the preceding week, and many patients began visiting the clinic with symptoms of physical imbalance.
The most important preventive measure is protection against the cold.
Is Sudden Lower Back Pain One of the Symptoms That Appear During Winter Doyo?
During the Winter Doyo period, temperatures continue to drop.
In regions such as Tohoku, Hokkaido, and Hokuriku, the land becomes covered in snow.
A severe cold wave also struck the United States on January 24–25, 2026, and President Trump declared a state of emergency in 24 states (as of 12:30 p.m., January 26, 2026). In parts of New York State, temperatures reportedly fell to –45°C.
When the body is unable to adapt to a sudden drop in temperature, a variety of symptoms may appear, such as:
- Sudden lower back pain (acute lumbar strain)
- Cold hands and feet
- Heaviness in the back of the neck
- Leg cramps at night
- Increased nighttime urination
- Elevated blood pressure in the morning
- Muscle and joint pain
- Difficulty concentrating
- A general feeling that the body does not move as freely as usual
During this season, Eastern medicine considers that people whose spleen function is weakened tend to feel generally unwell. Digestive problems and diarrhea become more common, and many people experience pain in various muscles.
In many cases, medical examinations reveal no abnormalities, and there is no specific medication to prescribe. In simple terms, these are people whose bodies are overwhelmed by the cold.
During the Doyo period, many people also find that long hours of outdoor work or exercise place a heavy burden on the body. In regions with heavy snowfall, snow shoveling may be required several times a day.
In 2026, heavy snowfall has been reported in many areas, and it is easy to imagine that many people are experiencing considerable physical fatigue as a result.
In areas without snow, people may enjoy walking or exercising outdoors. However, when outdoor temperatures fall below freezing, it is advisable to avoid unnecessary outdoor exercise.
This is especially true for individuals experiencing symptoms 2 through 9, as exposure to extreme cold may aggravate their condition. It is better to exercise during the warmer hours of the day.
During Winter Doyo, people whose spleen function is balanced and whose liver, kidneys, and heart are strong often experience an increase in digestive activity. In cold weather, appetite naturally increases as the body works to maintain its temperature.
For individuals who are underweight, gaining some body fat can help protect against the cold. On the other hand, those who are prone to weight gain may tend to overeat during this season.
Winter Doyo falls between January 16 and February 3, shortly after the December holiday season and around the time of the Chinese New Year. People who gained weight during the holidays and continue overeating may find that their weight increases further, which can contribute to the symptoms listed above.
It is important to pay attention to portion sizes and to avoid excessive consumption of foods that cool the body, such as certain fruits. Overeating may also place a burden on kidney function.
For more detailed information, please refer to my previous blog posts, where I have discussed these topics in greater depth.