You wake up surrounded by loved ones. But this reunion carries a dire warning: you can't stay. Your time here is limited. A searing pain rips through your body as you gasp back to life in a hospital bed. You were dead just moments ago.

This phenomenon is called a near-death experience. Countless people report leaving their bodies upon death. They recount bright lights, visions of heaven, and conversations with spirits. This happens across cultures and belief systems. But what explains these common threads?

Are near-death experiences proof of the afterlife? Or could they be explained by science? Recent brain scans of dying patients revealed surprising surges of activity after death. Their final, mysterious moments suggest more questions than answers about what lies beyond.