Being a “morning person” or “evening person” is a behavioral consequence of a person’s underlying circadian rhythm, which is shaped by their genes. Some genes can even shift a person’s natural waking time by up to 25 minutes.

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Being a “morning person” or “evening person” is a behavioral consequence of a person’s underlying circadian rhythm, which is shaped by their genes. Some genes can even shift a person’s natural waking time by up to 25 minutes.