Every ninety minutes, the crew orbiting high above Earth watches another sunrise break over the planet, which means that in a single day they see sixteen dawns and sixteen dusks, and their bodies have no idea what time it is anymore. - Space Daily

Every ninety minutes, the crew orbiting high above Earth watches another sunrise break over the planet, which means that in a single day they see sixteen dawns and sixteen dusks, and their bodies have no idea what time it is anymore. Space Daily