function _watchUserInput(){
        if(htVar.nTimerInput !== null){
            return;
        }

        htVar.nTimerInput = setInterval(function(){
            var nFromLastInput = (new Date().getTime() - htVar.nLastInput);

            if(!htVar.bSleep && nFromLastInput >= 60000){ // get sleep if no input in 60s
                _deactivateTimers();
                htVar.bSleep = true;
            } else if(htVar.bSleep && (nFromLastInput <= 1000)){ // wake up if new input detected
                htVar.bSleep = false;
                _activateTimers();
                return;
            }
        }, 500);
    }
start to watch userInput
deactivate all timers automatically if no user input in 60sec,
and reactivate when any input has detected