During hot summer season, we often feel sleeping difficulty, not sleeping well, or waking up not rested. The reason for those may be "over heated brain".

『Over heated brain』
When your brain is over heated, your body cells and organs system performances become low, causing several un-wellnesses. The initial symptoms are hot flashes like taking a hot bath and spaced out feeling when you have a blocked nose. As the symptoms appear for a long term, it may lead to dysautonomia, slump of organs such as heart, lungs, stomach and so on, and poor body temperature regulations causing heat stress easily. It also causes summer fatigue and mental run down with tiredness, dizziness, headache, tinnitus, disorientation, poor blood circulation, and so on.

Brain temperature is a core body temperature which is normally the lowest when waking up, rising after getting up from bed, and start declining after the peak time 16:00. As the core body temperature declines, your body is naturally lead to sleep. As the core body temperature drops, body gets naturally ready to sleep, and brain gets cooled down while sleeping. If your body have troubles getting heat out of the brain, it affects your body such as having troubles falling asleep and waking up at night distracting your sleep. Not even stress and heavy smartphone usage, hot weather and humidity is also the risk of causing over heated brain.

『Brain cooling』
- The temperature for brains is 23-24℃/humidity 50% -

The easiest way of cooling your brain is to breath from nose in a well air-conditioned room. Breathing from nose can cool the center of autonomic nervous system directly. A brain can be cooled down by breathing cool air in from nose as an overheated computer and refrigerator get cooled down by a built-in fan.

ーIncreased productivity at 25℃ー
Nose breathing is important to cool a brain. The recommended room temperature is 24℃ considering that we likely to breath from mouth when it is hot and the fact the air breathed from nose get slightly warmed by nose hair and mucous membrane. Therefore, during the summer in Japan, we need to set the room temperature lower. Some people do not prefer lower temperature and the reason behind that is unlikely them not having enough mussels feeling colder than it actually is. It surely depends on each person how they feel. However, the best temperature for a brain is the same to everyone.

ー28℃ room temperature is not completely safeー

It is almost a common sense to set a room temperature to 28℃ to save electricity bills. However, 28℃ is the temperature with heat stress risks. We must understand that it does not ensure the safety of not suffering heat stress. If you suffer from heat stress and ended up hospitalized, the cost is way bigger amount than electricity bills. According to scientific research, human productivity become 2% lower as temperature rises every 1℃ from 26℃. When 28℃ which means the human productivity becomes 4% lower, results over work using Electricities longer and costing more money. Hyogo prefecture Himeji city hall has conducted an experiment of setting the room temperature for 25℃ in July and August in 2019. The result of the experiment was that the productivity, and the performance had improved decreasing 14.3% overwork hours, and saving ￥40,000,000. Referring to scientific research, many multinational companies tend to set room temperature lower in summer, considering its cost performance.

ーCooling head and warming lower than neckー
While sleeping it is only the head to cool. Rest of the body needs to be warm. Cooling under arms and neck is effective as blood is also cooled down. However, it cools the whole body. It has bad affect for blood fluence, organs, and autonomic nervous system when it is too cold. Wearing long sleeves and use blanket in 24℃ room is recommended. Temperature differences can be a stress, so we need to prepare for going outside. Set the temperature low to sleep using winter bedding is preferred.

ー4・7・8 breathing techniqueー
Breath from nose for 4 seconds, hold breath for 7 seconds, and breath out from mouth for 8 seconds to cool brain and relax. It is effective when feeling run down, overheated, and after exercises as well as relaxing before bed.

Cool your brain and stay healthy and happy.