As summer arrives in full, we are entering the season when staying hydrated becomes especially important.
Water is essential to our bodies, and in recent years it has become known that it is also closely tied to the condition of the brain, not just the body.
For example,
• Your head just does not seem to be working
• You cannot stay focused
• Your head feels heavy by late afternoon
• You tire easily
states like these may be related to not drinking enough water.
About 75% of the brain is said to be made up of water, and research has reported that even mild dehydration of around 1–2% of body weight may lead to reduced concentration, attention and cognitive function, as well as increased fatigue.
For this reason, staying hydrated is considered an important element in looking after the condition of the brain as well as the body.
You may have heard the advice to “drink 2 liters of water a day,” but the amount of water you need varies depending on sex, build, activity level, temperature and other factors.
In the Dietary Reference Intakes for Japanese published by Japan’s Ministry of Health, Labour and Welfare, the following are given as guidelines for total daily water intake:
• Adult men: about 2.5 L
• Adult women: about 2.0 L
These are the figures it provides.
However, these amounts include not only beverages but also the water you get from food.
So, as a rough guideline for beverages alone, it may be easiest to think of about 1.2–1.5 L for men and about 1.0–1.2 L for women.
In summer you also sweat more, so it is important to be even more mindful of staying hydrated than usual.
In particular,
• After waking up
• Between tasks at work
• Before and after bathing
• Before and after exercise
are recommended times to drink water.
People today process a great deal of information every day through work, smartphones, social media and more.
That is why it is important to think of hydration, along with sleep and rest, as part of looking after your everyday condition.
As the hot season approaches, why not start with the simple habit of drinking a glass of water?