npr has an interesting article on some recent research about what happens when humans sleep in an unfamiliar place. It’s long been known that humans don’t sleep well in an unfamiliar place. The effect is so common it even has a name: “first-night effect.” Sleep studies have long thrown out data from subjects during their first night in the sleep lab. The new research explains why this happens.
It turns out that half our brains are standing guard. This is completely understandable on evolutionary terms: when in a new place our ancestors were unfamiliar with the predator risks so only half their brains went to sleep. The other half, the left half, stayed alert and watchful. This happens with many birds and mammals but has never before been documented in humans.
The npr article is short and worth reading just for the details. The actual paper goes into more detail, of course, but seems well tracked by the npr story. The npr story describes the experiments the researchers performed to reveal the effect. The takeaway is that you can expect to sleep less well your first night in a new place and that the effect is involuntary and can’t be avoided.