Why jetlag exists?

shape shifters

Jetlag exists because our bodies have a brake that slows adjustment whenever we move into a new rhythm of darkness and light. It’s a form of resistance to change: the body shifts cautiously into the new rhythm, and it is that caution that prevents our rapid adjustment to a new ambient time zone. If body clocks were able to reset quickly and easily our ancestors might have been thrown out of kilter by a full moon, or whenever they enjoyed a late night around their Palaeolithic fires. But our body clocks have to be able to shift – without that malleability we could never have moved from the tropics to the temperate and polar latitudes as a species, where there are rapid swings in sunrise and sunset times around each equinox.

Shape shifters