打哈欠并不总是意味着你累了。这种下意识的行为是很多不同感觉中的一种表达。Yawning doesn’t always mean you are tired. This involuntary action is an expression of many different feelings. People often yawn when they don’t agree with a person or when they feel bored. They may also yawn when they are angry or nervous. Some scientists believe that yawning cools down the brain. Yawning is often followed by stretching, which may be exactly what the body needs when it is upset, bored, or nervous. Yawning is a
contagious1 reflex. When you see someone yawn, it often causes you to yawn. In fact, just thinking about yawning can make you yawn! Psychologists believe yawning is a way of showing empathy. Contagious yawning is not just a human phenomenon. Almost all vertebrates yawn. Some theories suggest that yawning helps animals stay alert. Yawning awakens2 many parts of the body, including the jaw3, lungs, and abdominal4 muscles. Opening the mouth wide also allows animals to bare their teeth. Next time you yawn, ask yourself this question: What am I trying to communicate?
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