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In the study, published in the journal Current Biology, researchers observed the brain waves of their participants. The two brain hemispheres showed stark differences. The left displayed signs of wakefulness while the right showed signs of sleep. It is this left side—the one that remained alert—that acted as a "night watch" patrolman during the sleep, leading to an unfulfilling snooze session.
"The environment is so new to us, we might need a surveillance system so we can monitor the surroundings and we can detect anything unusual,"says Masako Tamaki, one of the study's author.
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It's a habit that's often displayed in larger animals, the scientists noted. The left side of the brain remains vigilant and observant of the new surroundings while the right side snores away. But the imbalance between the two is why you wake up feeling much groggier and tired than after a night at home.
Good news, homebodies: Now you have an excuse to head back home.