The young men all deny they are going to fall asleep Dr Reyner has a video recording of one trying not to At first the person at the wheel is very upright wet and bleary eyes determinedly fixed on the windscreen Then he begins to blink briefly every now and again then for longer and more often with a slight drop of the head Each nod grows heavier than the last The blinks become a 10second blackout Every time he jerks awake as if nothing has happened But the car by the second or third occasion has shot off the carriageway