I'm not claiming to know the answer, but I think each of us imposes our own experience on our ideas, and sometimes fail to take into account that everyone is different.
I used to work full time nights, (and did so from choice, not economic necessity). I worked 11 pm to 7.30 am, and then worked part time for a car rental agency recovering or delivering cars.
I was often asked if I felt tired, or was in danger of falling asleep.
No. Never. My sleep pattern consisted of 5 - 6 hours a day, and had done since I can remember. Why people think you should go to bed as soon as you finish nights is beyond me. How many of us finish at 5.00 pm then go home to bed?
Some may well have noticed my nocturnal posting here!! I see others posting late too, so maybe I am not alone in this?
When I go on holiday, I drive through the night from Windermere to the south coast. After working nights for 6 years, I recognise immediately if I am losing "the edge" on my alertness - and take steps to rest - either while my wife drives having slept from setting off, or after a half hour in a MSA. I think the technical term is "power napping" and it works - FOR ME. Maybe it does for Paul too.
I would NOT advocate this as a suitable course of action to anyone else, as their physiology is bound to be different to mine.
IMHO, the worst that can happen to anyone is to have so little time to get to their destination, that they feel obliged to press on instead of stopping for as long as is necessary, and that requires driver education not extended waiting times at MSA's