On a false Wednesday, an actual Thursday. Chun Yujun, who was reluctant to get up, opened the curtains, saw that the sky was gloomy, heard the murmuring of the rain, and even more did not want to go to work and wanted to go back to the bed to sleep!! after coming to the company, he found that his colleagues generally came later than usual, and he couldn't get up when he asked.
Wanting to sleep on a rainy day seems to be a common phenomenon. So, what is the magic of a rainy day that can make people dazed and not want to open their eyes?
One layer of magic: dim
Melatonin is a hormone secreted by the pineal gland of the human body, and in the 70s of the 20th century, studies found that the production of melatonin is related to the body's circadian rhythm. Melatonin, as a synchronizer of the biological clock of the human endocrine system, has a wide range of physiological activities, the most famous of which is the regulation of sleep.
The secretion of melatonin is affected by light in a circadian rhythm, usually the concentration of melatonin in the blood drops to the lowest point at 8 o'clock in the morning, begins to secrete at about 20 o'clock in the evening, and then gradually begins to rise, rises rapidly after 23 o'clock, peaks at 2-3 o'clock in the morning, and then gradually declines, and the sleep gradually becomes lighter, until the morning naturally wakes up.
Melatonin secretion increases at night, but is suppressed whenever the eyeball sees light. Therefore, if you wake up frequently at night and turn on the lights (or play with your phone all the time after turning off the lights), it will significantly affect the secretion of melatonin, resulting in difficulty in falling back asleep.
In the same way, rainy days are often cloudy, and if you tighten the curtains, the indoor light is almost the same as at night, your mobile phone, your alarm clock, your brain knows that this is daytime, but your eyes don't know melatonin, it's still secreting diligently, trying hard to make you sleep, who can resist such sleepiness!
Double Magic: White Noise
White noise refers to random noise in which the power spectral density is uniformly distributed across the entire frequency domain, with the same energy density at all frequencies. Contrary to harsh, noisy and annoying noise, white noise not only does not make people irritable, but also soothes the nerves, calms the mood, and produces an auxiliary hypnotic effect.
While there is no such thing as absolute ideal white noise, there are many sounds in nature that come close to white noise, such as waves crashing against rocks, mountain streams, insects in the woods, and rain.
The sound of dripping rain, evenly repeated and low (no thunder), especially when alone, can easily make people sleepy. Similarly, for some people who have trouble falling asleep, playing a soothing sound of rain (or white noise such as running water, waves, and insects) may improve sleep quality to some extent.
Triple Magic: Low Oxygen
When it rains, the air pressure decreases, the plant photosynthesis is relatively weak, and the oxygen content in the air is relatively low, which makes our brains more "lazy" and the sympathetic excitability decreases.
The activity of the sympathetic nervous system is mainly to ensure the physiological needs of the human body in a state of tension, once its excitability is reduced, you are not anxious, your energy is not concentrated, you feel bored, don't you just want to sleep.
In addition, there is also a theory that rainy days will increase the content of negative ions in the air, so that people feel more comfortable, relaxed, and sleepy, but there is no definite research conclusion on the effects of negative ions on various health effects of the human body, especially the effects of anxiety, relaxation and sleep.
In short, rainy days not only make people feel sleepy physiologically, but also restrict people's travel activities, and people naturally want to stay indoors (preferably not going out), so it is certainly a good choice to get some sleep.
Don't go, there are small easter eggs at the end of the article~
Can melatonin "blacken"?
In 1958, Aaron Lerner, a dermatologist at Yale University, and others isolated a substance that can fade frog skin from the pineal gland extract of bovine brain and named it melatonin. In amphibians, the action of melatonin is antagonistic to melanocyte-stimulating hormone and can fade the skin, but alas, melatonin does not fade the skin tone of mammals.
Source: Yitu.com
Editor: Dr. Chunyu
Bibliography:
[1] Park YM, White AJ, Jackson CL, Weinberg CR, Sandler DP. Association of Exposure to Artificial Light at Night While Sleeping With Risk of Obesity in Women. JAMA internal medicine. 2019
[2] Zhao Zhongxin. Sleep Medicine. Beijing: People's Medical Publishing House, 2016. [3] Popular Science China, Why People Are Easier to Fall Asleep on Rainy Days, 2019-03-08, https://cloud.kepuchina.cn/search/imgText?id=458119