Check out 13 myths and facts about heat

We are in the middle of the first heat wave this year. Some are happy and some suffer. Sleep researchers, rescuers and emergency physicians say what heat does to our bodies.

Bruno Knellwolf / ch media

You can not go in the water for two hours after eating.

No, this old bathing rule is no longer valid, says Rito Abcherli, general manager of the Swiss Life Saving Society (SLRG). The rule now applies: “Do not enter the water under the influence of alcohol or drugs! – Do not swim with a full or completely empty stomach. »

Rain for two hours before taking a shower is no longer appropriate.Photo: cornerstone

Even if the two-hour period is no longer in effect, the body still needs more energy to digest after eating. For this reason, one often feels tired and sluggish after a sumptuous meal. “Because of the reduced blood flow to the brain, exercising soon after a meal can lead to dizziness and nausea,” Abcherly says.

“The worst thing you can do is faint in the water and drown in silence.”

On the contrary, you should not swim on a completely empty stomach, since hypoglycemia in the water can lead to “starvation”.

Climate shocks are bad, so don’t jump in the deep end when you’re very hot.

This is correct. “Never jump in the water when you are overheated! The body needs time to adapt,” is the rule of showering. “If you jump into cold water when your temperature rises, the difference in temperature between the air and the water creates a stressful state for the body,” says Abächerli. However, not every body reacts the same way. What can happen when you jump into the water when the temperature rises are muscular reactions such as muscle cramps and/or circulation problems. Since the veins have suddenly narrowed, the blood is no longer able to circulate properly. In the worst cases, this can lead to cold shock, fainting, or a heart attack.

As a precaution, showering before getting in the water will cool you down accordingly. Otherwise, slowly enter the water, alternately dipping your arms and wetting your face and upper body with cool water before submerging completely.

Before you jump into the water, it must be cooled.

Before you jump into the water, it must be cooled.Photo: cornerstone

Anyone who quickly moves into extremely cold rooms is detrimental to their health.

No. “In order to balance body temperature in the summer, the body must cool off,” says Elk Schmid, chief physician at the Central Emergency Room of the Cantonal Hospital of St. Gallen. The body does this by transferring heat away from the inside of the body to the outside by increasing blood circulation in the skin. We produce sweat, this film on the skin also has a cooling effect. If we now come to a very cold environment, the organism will try to maintain its core temperature at 37 degrees Celsius, and for this purpose it stops the blood flow in the skin. “Because of the layer of sweat on the skin, we perceive this room temperature to be colder,” says the emergency physician. It’s not a climate shock. As mentioned above, this can happen when a hot object is immersed in cold water.

In the summer you need less sleep than you do in the winter.

yes. “In our latitudes, many people in surveys say they sleep less in the summer than they do in the winter,” says sleep researcher Christian Cajochen from the University of Basel. On average it is about 20 minutes less. According to Cajochen, there are many reasons for this: more daylight in the evening and morning, more social events that last longer in the evening, and the Mediterranean lifestyle. There is more happiness hormone serotonin and other activators. “Therefore, the ‘winter blues,’ which are associated with hypersomnia, that is, too much sleep during the day, is reduced,” says Cajochen. For healthy people, a short sleep in the summer is not a problem. In the summer, people will have more vacations and therefore more time to nap and make up for sleep during the day.

In the summer, you actually need less sleep than you do in the winter.

In the summer, you actually need less sleep than you do in the winter.Photo: cornerstone

Normal sleep is not possible on such hot nights.

that’s right. In our latitudes, we are not used to tropical nights. “Our temperature regulation really works to make us sweat, even at night,” says sleep researcher Christian Cajochen. To get a good night’s sleep, the body must be able to emit heat within as ideal a temperature range as possible. This works best at room temperature of 18-20°C with gentle humidity. “The body cools down a lot underneath, and you freeze. The opposite is the case at higher temperatures, both of which lead to poor sleep with many interruptions,” says Caguchin.

I’m always in the shade anyway. I don’t need sunscreen.

No, even in the shade we are exposed to ultraviolet rays that can burn our skin. Due to the reflection of ambient radiation, we are still exposed to up to 50 percent of UV rays despite the canopy. So it must be rubbed. This also applies to the shades of trees and under passing clouds. Even water does not provide protection from the sun’s rays, and it can even increase radiation. Even when diving, you are not protected, because at a depth of half a meter, 40 percent of ultraviolet rays still penetrate.

Even those in the shade should not do without sunscreen.

Even those in the shade should not do without sunscreen.Photo: Environmental Protection Agency

I put lotion on all the time, so I can lie in the sun for a long time.

No. The most important thing is the first application. And you should do it early enough, because it takes about half an hour for the sunscreen to build up protection. However, you lose protection when you shower, sweat and dry out. For this you have to apply the cream again, even if the product says “waterproof”. How often you have to rub it depends, among other things, on the sun protection factor of the cream. The higher the value, the higher the protection. In fair-skinned people, unprotected skin reddens after five to ten minutes. SPF 30 extends this time by about 30 times. So a person can stay in the sun for 300 minutes.

Heavy application is not good.

this is not true. Sunscreen can be applied generously. In order to achieve the limiting factor of sunscreen, a person with a height of 1.80 meters needs about 40 milliliters for the entire body.

On hot days I have to drink four liters.

yes. On normal days, 1.5-2 liters is enough. At high temperatures above 30 degrees, twice the amount is recommended. Our body is made up of more than 50 percent water. Water in the body is responsible, among other things, for regulating body temperature and thus protects the body from overheating. This is why it is important to drink a lot on hot days. Due to increased sweating, the body loses a significant part of the absorbed fluid. It is important not only to drink a lot, but also regularly. But you shouldn’t overdo it either. Excessive fluid intake can put extra strain on the heart and kidneys.

When the temperature is high, the water bottle should be sufficiently filled.

When the temperature is high, the water bottle should be sufficiently filled.Photo: cornerstone

Hot drinks are better than cold drinks in the heat.

this is not true. When we drink hot coffee or tea, we sweat more and it becomes difficult for our bodies to compensate for the fluid loss. But cold drinks aren’t better either. A cold drink does not stop sweating. exactly the contrary. With a cold drink, the body assumes that it must produce additional heat, which is why we are so overheated. Lukewarm drinks are best. But be careful with lukewarm beer: Alcohol makes you drink faster in hot weather, makes you flabby and makes you sweat.

You should refrain from practicing any sport in the heat.

No. However, jogging at lunchtime or in the evening is not recommended. On a hot day, a lot of ozone is formed at ground level: an irritant gas that can cause breathing difficulties. The longer the day, the longer the day. However, in the morning, ozone levels are still low, so a round of jogging can be tolerated well.

Heat stroke is the same as heat buildup.

No. “Direct sunlight on the head causes heat to build up in the brain and thus irritates the meninges,” says emergency physician Elk Schmidt. However, headache, nausea and vomiting do not occur until after a certain period of time, that is, after hours. On the other hand, heat accumulation occurs even without direct sunlight if body temperature regulation is disturbed due to prolonged exposure to heat.

Direct sunlight on an unprotected head can lead to meningitis, which is meningitis, which in particularly severe cases can lead to permanent brain damage. Symptoms of heatstroke are crimson, hot head, neck pain, headache, and dizziness. Babies are more at risk because their skulls are thin and provide little protection from the sun.

Short, white clothing is best in hot weather.

Not quite right. Dark colors absorb ultraviolet rays faster and more intensely, and black pants heat up. At the same time, dark colors reflect the infrared part of the radiation, which is why the body is better protected from sunburn. The shorts are breathable and comfortable. But the more skin you have on it, the more spots you need to burn. So the Bedouins do not walk around in shorts, but rather loose, airy clothes. Layers of different textiles allow air to circulate and cool the skin. (

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