Yes! Years ago I took a small dose of Ativan. It so happened that my niece and I were attending a Native American festival that day. The last thing I remembered was the sound of the car doors slamming when we got out of the car to walk to the festival. Next thing I knew it was morning of the next day, I awoke in my bed, and never recovered anything of the festival we attended for several hours. My niece never said anything, so I assume I behaved normally.
I have been taking Klonopin for around twenty years and it has caused me to lose so much time in my life. Just complete black-outs. It makes me sad.