I have made the following test: Select a unit, press shift (to queue orders) and select move to a tile (first order) and then fortify (second order). After the end of the movement order: If the unit has remaining move points, it fortifies. If the unit has depleted its movement points, the next turn the unit awakes (instead of fortify). For example, select a settler and order it to move it 3 tiles (with no movement penalty, like grasslands or plains) away and then sleep: The settler reachs the destination in the second turn and sleeps. Instead, select a settler and order it to move it 4 tiles away and then sleep: The settler reachs the destination in the second turn and then awakes in the third turn. I think this is a bug: The settler should have to sleep at the beggining of the third turn.