Summer lethargy, "Natsu-bate (夏ばて)"

How is everyone surviving the summer so far? Feeling tired, lack of energy, no appetite, having occasional diarrhea, constipation, or dizziness and headache? If you are, then you are probably going through this summer lethargy which most of the people would experience more or less during summer in Japan.

Summer lethargy is called “natsu-bate” in Japanese. Natsu-bate is a shortened word from “natsu”, meaning summer, and “bateru”, meaning exhausted.

There is no exact definition of “natsu-bate”, but rather, it is a collective term used to describe a few distinctive symptoms people experience during summer, as mentioned above.

In general, the three main causes that can lead to “natsu-bate” are said to be:

1. deficiency of body water and minerals
2. decreased digestive function and nutritional deficiency due to heat
3. roller coaster of temperatures inside and outside of an air-conditioned room.

Other reasons include stress, lack of sleep, and sharp climate changes in rainy season and early summer, etc.

Among all the perceived possible causes, roller coaster of temperatures inside and outside of an air-conditioned room is considered the easiest to lead to “natsu-bate”, as this puts the body’s autonomic nerve system off balance. When being placed in a high temperature or high humidity environment, the human body experiences certain strains as the body energies are consumed in order to maintain the body temperature. Being exposed constantly in sharp changes of temperatures between air-conditioned room and boiling weather outside can easily disrupt the system, making the body unable to regulate the body temperature, therefore resulting into the various “natsu-bate” symptoms.

In more extreme cases where the body is exposed to excessive heat and is producing or absorbing more heat than it can dissipate, it can lead to an acute condition called heat stroke, or sun stroke. Heat stroke is a medical emergency that requires immediate medical attention.

Prevention/ Improvement of “natsu-bate”:

• have plenty of rest and take plenty of well-balanced nutrition
• drink plenty of water to replace lost fluids from sweating. Water, not sports drinks.
• drink warm drinks instead of cold drinks, as this is effective in preventing excessive sensitivity to cold/ poor blood circulation, and can improve digestion
• use a lap rug or wear a thin jacket inside an air-conditioned room

You might think summer is going to be over soon, but don’t forget there is this late-summer heat called “zansho (残暑)” which is probably going to stay on for some time still, so, take the best care and enjoy the rest of the summer!