Special relativty theory says, how to transform the mesurments from one inertial systhem into another, or more explecit , what an observer in the outher inertial systhem would messure for time and room distances comperte with jour mesurments .
When your systhem, observed from the other,has nearly the velocity of light, the other observer for example will mesure, that your hour, has only 6 minutes , since you are in your systhem in rest , for youself there will be no effect !
The analoge effect works for things like length contradiction.
Unefected of this , there is (at least in special relativity theory) an great difference between the 3 room dimensions and the forth dimension the time , this is , that you can move in space in every direction you wan`t, but in time only foreward never backwards.
Merged post follows:
Consecutive posts mergedIf there would be a third inertialsysthem with another velocity then the two others ,an observer in it will measure also another "tempo" of time for the inertialsysthem were you are in rest ("or where you go to bed" ) then the other two , but that`s exactly what Albert Einstein told the world : in nature there is no room for Newtons absolute time (for his absolute room also not ) each observer has his on time .