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Yawning can be triggered not only by seeing another person yawn but also by hearing, thinking, or even reading about it. This is known as contagious yawning. Researchers continue to investigate why humans show this unusual response, with social and neurological mechanisms among the proposed explanations.
Not everyone is equally susceptible to it. The strange part is that no actual tired person needs to be nearby. Sometimes, the idea of a yawn is enough to produce a real one.
© Current Biology