1. The five traditional senses keep us alert and alive: Hot pans burn, loud noises startle. Within our bodies, a sixth sense, known as interoception, perceives the state of—and threats to—our internal organs. From pangs and cramps to shortness of breath, it warns us when something is off. Hungover from a wild bender? Waves of nausea in the presence of alcohol are interoceptive warnings to lay off the juice. 2.