Waking up suddenly in the middle of the night while in a hotel room, at a friend's house, or even in your old childhood bed can be a disconcerting experience. There's a rush of strangeness that brushes up against a feeling of panic: a sensation best summarized by the word disoriented. The tiniest sound might jolt you awake. Your internal compass seems to spin for a few seconds as you try to find your bearings and remember where you are. You wake up the next morning unrested: still shaking off the cobwebs that come with a night of poor sleep before you go downstairs to get your copy of USA Today and continental breakfast or to join your hosts who, of course, have slept very well. Luckily, the next night is usually much easier.
Scientists have discovered why we have difficulty sleeping in new places.
A team of researchers at Brown University recently published their findings about the "First Night Effect" in the journal Current Biology.
Using neuroimaging techniques, the researchers found that only half of the brain fully goes to sleep, while the other half remains partially awake as a kind of "night watch."
According to their findings, this function serves as "an act for survival over an unfamiliar and potentially dangerous environment by keeping one hemisphere partially more vigilant than the other hemisphere as a night watch, which wakes the sleeper up when unfamiliar external signals are detected."
In other words, the guardian hemisphere stays alert to protect you from potential danger.
Other animals also possess this faculty.
"We know that marine mammals and some birds show unihemispheric sleep, one awake and other asleep," said co-author Yuka Sasaki in a statement noted by Popular Science. "Our brains may have a miniature system of what whales and dolphins have."
Curiously, the researchers noted that, at least in humans, "the left hemisphere was more vigilant than the right when the (First Night Effect) occurred," but had yet to discover why.
Perhaps it's to try to keep us in our "right" minds when we wake up.
Either way, you'll feel better after your first night in a strange place and even more so once you return to the comfort of your own bed.