Why is it easy to get tired and sleepy when the weather is hot?

People live in nature, and temperature affects people's life, work and all activities all the time. In meteorology, the physical quantity representing the degree of air heat and cold is called temperature, which is referred to as temperature for short. The international standard unit for temperature measurement is Celsius (℃). The temperature mentioned in the public weather forecast was measured by a thermometer in a louver with a height of 1.5 m in an observation site with turf. Because the thermometer keeps good ventilation and avoids direct sunlight, it is representative, and this temperature basically reflects the temperature of the observation site (local). In the hot summer afternoon, the temperature in the small environment such as cement pavement and air-covered balcony is much higher than that in the louver, which is why some people think that the actual temperature does not match the temperature broadcast by the meteorological station.

So, what are the effects of temperature on human health?

In the high temperature environment, the human body should maintain the balance of body temperature through evaporation and heat dissipation. In the process of sweating, the salt in the body will be lost with sweat, the blood concentration and hemoglobin will increase, the blood viscosity will increase, and the burden on the heart and blood vessels will increase. This leads to a drop in blood pressure and increases the burden on the heart to maintain normal blood pressure. Human skin sweats a lot, which reduces the water discharged by the kidneys and affects the renal function. High temperature will also affect people's nerve activity and motor coordination.

In winter, the temperature drops obviously. In the low temperature environment, in order to keep the body's heat balance, tissue metabolism is strengthened and oxygen demand is increased. If the above conditions cannot be met, the human body will consume the reserves of cells in the body, thus causing irreversible changes in human tissues. In addition, due to the low outdoor temperature in winter, human blood vessels are easy to harden and become brittle, especially middle-aged and elderly people should pay special attention to adding clothes to keep warm. When the temperature is the lowest in the morning, outdoor morning exercises should be postponed to avoid life-threatening blood vessel rupture caused by low temperature.

Practice has proved that in hot summer, people's appetite is often bad, nutrient intake is reduced, resulting in a negative energy balance; When the temperature drops, the appetite of future generations will become strong after entering autumn and winter. The increase of nutrient intake can not only compensate the energy lost in summer, but also store the excess energy in the body under the skin, reducing the heat loss of human skin. According to the investigation of the Food and Agriculture Organization of the United Nations, when the outside temperature is higher than the standard temperature 10℃, the calorie intake of human body will be reduced by 5%; When the outside temperature drops by 10℃ compared with the standard temperature, the calorie intake of human body will increase by 5%. It can be seen that the intake of nutrients by human body has a great relationship with temperature. In addition, the temperature also affects the intake of vitamins and salt. In order to adapt to the environment, people in different climate regions have great differences in body shape, and the most important environmental condition is temperature.

The temperature drops obviously in winter, and the average outdoor temperature is below 10℃. In winter, the temperature is below 0℃, so people consume a lot of calories. Therefore, people have a good appetite. At this time, people should eat more high-protein animal foods and beans, especially hot mutton and dog meat, and middle-aged and elderly people should take some drugs regularly. At this time, northerners often use hot pot to rinse mutton and beef, which is beneficial to compensate for the consumption of human calories.

In a word, temperature has a great influence on human health. We should always pay attention to the change of temperature and take corresponding measures in time to ensure people's physical and mental health.