The First Night Effect Explained

When you sleep in a new place only half of your brain actually rests The other half stays

awake listening for danger Scientists call this the first night effect a leftover survival mechanism

from ancient evolution Animals like dolphins sleep with one eye open and humans still carry a version

of that instinct When you spend the night in an unfamiliar space a hotel room a friend’s couch

or a new apartment your brain does not fully trust it One hemisphere refuses to enter

deep sleep staying alert as a silent night guard That half listens to every creak every

rustle every change in sound It does not just hear it analyzes each noise deciding whether

it is safe or if it should wake you up That is why you feel tired after the first night