Ancient "mystics" knew this for ages. Using modern slang, it is an "environmental conditioning" and "habituation". Newly born babies presumably have no notion o

Ancient "mystics" knew this for ages. Using modern slang, it is an "environmental conditioning" and "habituation". Newly born babies presumably have no notion of time, except, perhaps, some bodily rithms, like states of sleep and being awake, but sleep too, has evolved the way it is partly due to day/night circle in our shared environment. Other creatures, notably deep water fish and mammals, have different mechanisms for "doing maintenance", like "switching between hemispheres", so they are never asleep (I am oversimplifying, of course). But it is clear that us and them have very different notion of time.