I never realise until I am there. Until I find myself feeling sick with disgust at my old interests and desperately seeking something to latch on to. If you know an autistic person, adult or child, know that the space between our passions is always terribly unsettling. Sometimes it feels bleak, for there is nothing to be excited about, nothing to dig in to. Sometimes it feels lonely, for we have lost our way of connecting with other humans. Sometimes it is scary, because we have taken away the only thing holding our mind tethered, keeping anxiety, or mania, or paranoia, or depression at bay.
I have realised something important about my needs. My mind needs FLOW to survive. Flow is the state we reach when we are completely immersed in something, sometimes called being 'in the zone'.