Why do you recognize the bed when you sleep?

A study shows that people usually can't sleep well in strange beds because half of their brains are still on duty, which is why some people recognize beds when they sleep. The "first night effect" is not unfamiliar to people who often travel and sleep in hotels and sleep researchers.

Now, a group of scientists are trying to figure out why people often have poor sleep quality on the first night in a strange environment. A series of brain scanning techniques revealed a surprising discovery: on the first night, the left side of the brain remained more "awake" than the right side.

This situation occurs in the stage of "slow-wave sleep" (also known as slow-moving eye sleep, which is generally characterized by decreased sensory function), making the left hemisphere particularly sensitive to sound. Therefore, any trouble is easy to wake the sleeper.

Scientists believe that in an unfamiliar and potentially threatening environment, our vigilant brains ensure that we remain at least partially alert at night.

For travelers who know the bed, scientists have given a possible solution: bring your own pillow when traveling. The idea is to give the brain a sense of security to ensure a good sleep.

Researchers say whales and dolphins also keep one side of their brains awake when they sleep. The most likely reason is that even during sleep, they need to surface to breathe regularly.

They pointed out that this discovery only solved part of the mystery. They only measured the first phase of slow-wave sleep, which occurs repeatedly during the sleep cycle. It is not known whether the left hemisphere stays vigilant all night or "changes posts" with the right brain in turn.