Almost every animal including insects and probably even plants seem to have an internal clock.
For humans, the internal clock can be changed by psychedelic drugs and the effect is to change our general perception of the world. Our world is structured around our timing mechanism.
For both nitrous oxide and THC our timing mechanism speeds up and therefore the world is perceived as slowing down. For nitrous oxide the timing mechanism can be made to goes so fast that time almost comes to a complete standstill and every moment seems to last for long periods.
In the case of some of mind enhancing drugs such as amphetamines and cocaine the timing mechanism seems to slow down and everything outside is perceived as being very energetic and excited... we are able to leap tall buildings in a single bound.
Because this internal clock is so universal in animals it is probably rudimentary It must be in the core limbic system. It is interesting to me that the mind that has evolved on top of this is so complex and able to create human societies. Yet the society is still dependent on our miniscule rudimentary timing mechanism.