Does the supermoon have "magic" powers? Is it the moon that causes poor sleep and sunburn from night running?

Audit expert: Peng Guoqiu

Deputy Chief Physician, Fourth Medical Center, PLA General Hospital

The second "supermoon" of the year appeared on the night of the Mid-Autumn Festival and September 18 this year. This year's Mid-Autumn full moon and the "supermoon" almost perfectly coincided, and such an astronomical phenomenon only occurs once every 60 years on average!

We know that moonlight is the reflection of sunlight by the moon. So will the supermoon reflect more sunlight, including a large amount of ultraviolet rays? Is the supermoon more likely to affect our lives?

Can moonlight affect sleep?

According to Life Times, a study published in the American journal Science Advances shows that people's sleep is affected by the changes in the moon phases: when the moonlight is brighter, people go to bed later and sleep for shorter periods of time. In other words, around the 15th day of each lunar month, people's sleep will fluctuate to a greater or lesser extent.

During sleep, even if we close our eyes, light can affect the brain through the optic nerve, disrupting the body's endocrine rhythm and biological clock, which will affect the quality of sleep.

Normally, the sympathetic nervous system is responsible for regulating physiological functions during the day, while the parasympathetic nervous system is responsible for regulating physiological functions at night. Therefore, the human body's heart rate tends to increase during the day and decrease during sleep at night.

However, if there is sufficient sunlight during sleep, the sympathetic nervous system may be activated even after falling asleep, and the brain may remain awake, causing the heart rate to increase, thus affecting the body's rest.

Does moonlight contain ultraviolet rays?

In this hot summer, the temperature is high during the day and relatively cool at night. Many young people choose night running as their first choice for physical exercise. But after running for a while, I found that my skin color seemed to have become darker despite avoiding the sun during the day. Could it be that I got tanned by the moonlight?

01

Why do people get tanned?

When sunlight hits the skin, the ultraviolet rays in the sunlight (mainly UVA and UVB bands) stimulate the melanocytes in our skin. These cells contain pigment particles, which are converted into synthetic melanin proteins. The more this protein enters the keratinocytes of the skin, the darker the skin color.

02

What is the difference between moonlight and sunlight?

The moon itself does not emit light, and moonlight is the reflection of sunlight from the moon, so the spectrum of moonlight is similar to that of sunlight. However, the moon itself absorbs some ultraviolet rays, so its reflectivity to ultraviolet rays is very small.

Let the intensity of the ultraviolet rays from the sun shining on us be X. When this X shines on the moon, it will be absorbed by about 93%, and 0.07X will be reflected. And because the moon is a spherical surface, a large part of the sunlight it reflects cannot shine on the earth.

Therefore, the intensity of reflected light is further reduced. After calculation, the intensity of moonlight reaching the earth is less than one fifty thousandth of sunlight . Such weak ultraviolet rays are not enough to stimulate the skin to produce melanin for defense, and thus cannot cause skin tanning.

So why do you get darker after running at night?

01

From the street lamp?

Generally speaking, street lights during night running are less likely to cause people to get sunburned.

The light emitted by street lamps is mainly for illumination, and the intensity of ultraviolet rays is usually much lower than that in sunlight.

However, if you run under street lights for a long time at night and are very close to street lights, you cannot completely rule out the possibility that a very small amount of ultraviolet light will have a slight effect on your skin. However, this effect is usually extremely mild and is almost negligible compared to the tanning caused by exposure to the sun during the day.

02

Hot wind?

If the hot wind is accompanied by high temperature and humidity, it may increase the body's sweating and expand the pores. In this case, if there is a certain amount of ultraviolet light in the surrounding environment (such as the afterglow of the sunset that has not completely disappeared, some strong artificial light sources, etc.), it may increase the skin's absorption of ultraviolet light, thereby indirectly affecting the possibility of skin darkening to a certain extent.

But in general, hot air alone is not the direct cause of skin darkening.

The real reason why your skin turns black when you run at night

01

Residual UV rays

There may still be a small amount of residual UV rays at night , especially in the period after sunset. If you run at night for a long time without taking proper protection, these residual UV rays may have a certain impact on your skin.

02

Sleep quality

After a night run, the body is in an excited state, which can easily lead to difficulty falling asleep or shallow sleep, affecting the liver's detoxification and metabolic capacity, which in turn affects the body's recovery and conditioning, and may cause the skin color to deteriorate. Poor sleep quality can also easily lead to endocrine disorders and changes in hormone levels, which may affect the production and metabolism of melanin, causing the skin to darken.

03
Environmental factors

If the night running environment is poor, such as severe air pollution, pollutants may adhere to the surface of the skin, affecting the skin's normal metabolism and self-repair, indirectly leading to poor skin condition and a darker appearance.

04
Bad habits after night running

If you don’t clean your skin immediately after running, the mixture of sweat, dust, etc., which remains on your skin, may clog your pores, cause inflammation, and lead to pigmentation.