One senior safety campaigner accused drivers of "ignoring the lessons of the Selby rail crash".
The findings come in a survey of 500 drivers questioned on the M1 and M62 in Yorkshire.
Nearly one in five motorists admitted driving for more than the recommended two hours without a break.
Fatigue advice
When they did stop, 80% of drivers did so for reasons such as going to the toilet rather than to have a rest.
And only two per cent followed government advice on tackling tiredness such as drinking a caffeinated hot drink and having a 10 minute snooze.
The survey was commissioned by the road safety charity Brake and the Green Flag motoring assistance company.
Brake's chief executive Mary Williams described the findings as "shocking".
"They demonstrate drivers are ignoring the lessons of the Selby rail crash where 10 people lost their lives to a tired driver."
Nigel Charlesworth of Green Flag said: "These findings show that there is still a long way to go to making driving while tired an activity that, like drink-driving, is seen as unacceptable and anti-social behaviour."