When Astronauts go into space their Circadian rhythms ie their body clocks change from a 24 hour day to a 24.9 hour day which happens to be the rotation period of a single day on the Planet Mars. Since our body clocks are tuned to Planet Mars than to Planet Earth, does that mean that we were originally created on Planet Mars or some other Planet with a rotation period of 24.9 hours and then shifted to Planet Earth?
We were created on planet Earth from the start. We do not know the reason for these differences in circadian rhythms, but we do know that we have several types of people, some are morning people, and others are night owls, and a third type is in between. There are also what one would call a "dolphin" type... those who even when asleep have half of their brain on alert, and who tend to sleep little. Some of us are those dolphin types.
We assume that this was made on purpose so that there would always be someone available at night time to watch over the others, or help when the rest of the population were asleep (such as watching the fire while the rest of the tribe slept or fencing off enemies during the night).