In Trukz for every hour of driving in-game your driver will need an hour of real world rest. If you drive for 5 leg hours your fatigue level will rise to 5 fatigue points. It takes 1 real world hour of sleep (inactivity from the game) to lower your driver fatigue down one point. So, if you drive for 12 hours you will need to be inactive from the game for a total of 12 hours to have your fatigue points reset to 0 the next time you login. If you login to the game within 6 hours of your last leg your fatigue level will only lower 6 points.