Why do bed bugs hide in cracks and come out at night?

Bed bugs are adapted to living close to humans and other warm-blooded hosts. Their flattened shape allows them to squeeze into seams, cracks, baseboards and mattress edges, where they remain hidden during daylight. At night they come out to feed because hosts are usually still, reducing the risk of detection and injury. Bed bug infestations have been documented since ancient times, and the insects became a major modern pest again in the late 20th and early 21st centuries. Their behavior makes them particularly difficult to eliminate once they establish in a home or hotel.