Long distance in night with several drivers
Better without belt recumbent in the bed with a slept well driver than to risk with belts an accident with an overtired driver.
At many people an outcry of shocl: 4 sleepers behind without belts. What a bottomless carelessness! But let us look to the statistics of accidents.
Strategy A: Exchange the driver each 2 hours, 4 sleepers behind. Drive stady with the speed of a big bus. Practicall no danger of fall asleep acidents.
Strategy B: Nocturnal haste with top speed. The target has to be reached before falling asleep. What comes first? Calais or the sleep of the driver. Exchange the driver is sensless, because at high speed and siting is no recreative sleep possible.
I bet, that variant A has the much lower risk for all involved. The only risk is a head on colission with a vehicle coming against with sleeping driver after crossing the middle of the highway.