The universal feline response to a stressful situation is to withdraw and hide. When cats in the wild feel threatened, they head for trees, dens, or caves to seek safety. Indoor kitties don’t have that option, so hiding in boxes may be an adaptation. In addition, boxes and other tight spaces preserve body heat, and cats like it hot. Indoor kitties feel most comfortable when their environment is 86 to 97 degrees Fahrenheit. In this temperature range, your cat doesn’t need to expend metabolic energy trying to either warm up or cool down. Many cats also seem to enjoy surprising onlookers by suddenly springing from a box, while others like to dive in and out of them for exercise.