I take lorazepam on a 'as needed' basis. At night when I'm already tired but can't seem to turn my brain off, it will help me relax enough to fall asleep. In the day when I feel so anxious that I think it is affecting my performance, I take one to take the edge off. It doesn't seem to make me sleepy in those cases.
I've been pretty pleased with it. No noticeable side effects, does what I wanted. I've heard that there are better medications for this task than lorazepam, but ehhh I'm not inclined to try anything else.