It always made me sleepy. Except for the one time I accidentally took an extra one and thought people were breaking into our condo. We live on the 2nd floor of a secure building, so it's pretty tough to get in, but I could clearly see in my minds eye people wearing cartoony burgler outfits (black and white striped shirts with black eye masks) trying to break in.
I take Valium sometimes for anxiety (I get panic attacks) and accidentally took 2 within about a half an hour of one another because I couldn't remember if I had already taken it or not. Big mistake! Next time I forget, I'm skipping it. I was in La-La land for a while that day.