Yes it eill stop nightmares, but I feel I have to tell you to be careful with upping your ativan like that. There was a time in my life I was extremely reliant on this drug. It made me sleep, yes, but after 20 years of use it didn't work for anxiety, I feel it actually caused me to have anxiety and no use for good restful sleep. Its short acting and with that high of a dose you will continue to need more and more of it to work. A few years ago I had enough and looked into what I could do. Switching to diazepam was a good choice for me. I tapered down slowly and don't get that feeling anymore that I cannot live without it. Take care