Babies' Slightly Higher Body TemperatureThe Comfort Temperature is the Same for All

Since babies cannot regulate their body temperature well, it’s ideal to adjust the room temperature instead and dress them as lightly as possible.
Babies under one year old have difficulty adapting to extreme heat in summer and cold in winter, so please pay special attention to room temperature. Their body temperature is easily affected by air temperature and humidity, causing fluctuations in their physical condition.
Although babies’ body temperature is slightly higher than that of adults, the temperature they feel comfortable with is the same as adults. Be careful not to make it too hot or too cold.

As for humidity, the comfortable level for babies throughout the year is 50– 60%.
A baby’s skin is about half as thick as an adult’s stratum corneum, making it delicate and sensitive to irritation.
While ensuring good ventilation, use a humidifier or dehumidifier to maintain a comfortable humidity level.

Adjust With Room Temperature, Clothing, and BeddingHow to Spend the Winter & Summer Seasons

〈 Winter 〉
When using an air conditioner or heater during winter, a temperature of around 20–25°C is ideal. However, since the air tends to become dry, use a humidifier together.
It’s common to overdress or overheat babies in an effort to “keep them from getting cold.”
If you put your hand on your baby’s head or back and feel sweat, it’s a sign they are too warm. When it gets too hot, redness may appear in the folds of the neck, underarms, or groin. Also, touch the soles of their feet—while they may feel hot when sleepy or unwell, if they are warm otherwise, it may indicate overheating. Be mindful if your baby seems fussy or restless; they may be too warm.
Overheating can increase the risk of sudden infant death syndrome (SIDS) or heatstroke, so please be careful.
When a baby is cold, their complexion and lips may become pale, and their stomach or back may feel cold. Cold hands and feet alone don’t mean they are cold, so don’t worry.
In winter, dress your baby in soft cotton underwear suitable for the season, put pajamas over it, and adjust with a sleeping sack or blanket.
Avoid overheating or overcooling—keep a good balance.
Signs that your baby is cold include:

• ○ The stomach or back feels cool
• ○ Lips or face look pale
• ○ Shivering

If these signs appear, raise the room temperature or adjust their clothing or bedding.


〈 Summer 〉
In summer, be careful not to make the room too cold compared to the outside temperature. The recommended air conditioner setting is 25–28°C, but around 4–5°C lower than the outdoor temperature is appropriate.
During the rainy season and summer, pay close attention to humidity, which can cause mold.
The comfortable humidity level is around 50–60%. When it exceeds 60%, babies may feel uncomfortable.
Use a dehumidifier when humidity is high during the rainy season or summer.
Make sure the air conditioner’s airflow does not hit the baby directly. Use it wisely so the cool air doesn’t reach their body directly. If their exposed hands or feet get too cold, the brain sends a signal to “raise body temperature,” causing an increase in body heat and sweating on the back. Babies will cry if they feel too hot or too cold, so if they seem content, there’s no need to worry.
Signs that your baby is too hot include:

• ○ Face is red
• ○ Head or neck feels hot
• ○ Stomach or back is sweaty

Try lowering the room temperature slightly, switching to lighter clothing, or reducing bedding.

Develop a Habit of Checking Your Baby’s Conditionby Touching Their Hands and Feet

Place a thermometer or hygrometer at the same height where your baby sleeps and check the environment regularly.
A baby’s hands and feet are sensitive to outside air and serve as sensors for temperature regulation. Even if they feel cold, it means blood is being directed to the body’s core, so the body should still be warm. If their hands and feet are cold but their stomach or back feels warm, the baby is generally comfortable.
When the body is hot or sleepy, blood vessels in the hands and feet expand to release heat and lower body temperature.
Get into the habit of touching their hands and feet to understand their current condition.

A baby’s normal body temperature is about 36.3–37.4°C, though it varies from baby to baby. Remember your baby’s usual temperature—if it’s about 1°C higher than normal, they have a fever.
However, being in a hot room or wearing too many clothes can also raise body temperature, so consider the situation.
If a fever over 38°C continues and the baby seems irritable or refuses milk, contact a medical facility immediately.
By spending time with your baby when they are healthy, you’ll learn whether they tend to feel hot or cold and what environments they prefer.