PHWhen you travel, your brain is on alert
It's called the "first night effect," according to a 2016 study published in Current Biology, and it's because one side of your brain remains active in order to react to potential dangers in a novel environment.
The left side of your brain stays more awake for the first night in an unfamiliar place, so you're kind of sleeping with one eye open—in a way.
(S) bestlifeonline