Benzos affect the part of the brain responsible for forming memories. This is why some (Such as Rohypnol a.k.a. "Roofies") are used as "date rape drugs" because not only can the knock someone out, or severely sedate them, but they also make it nearly impossible to remember what happened. ESPECIALLY in combination with alcohol... While this is not ALWAYS an issue, when a large/larger dose is taken, it is VERY common and isn't something to worry about too much. Not that worrying would be much of an issue since benzos work on the GABA receprots, much like alcohol, lowering anxiety and stress.