Avenged Sevenfold's 2010 chart-topper 'Nightmare' was a deeply personal album for the band, as it was recorded while the remaining members rebounded from the tragic and untimely death of drummer Jimmy "The Rev" Sullivan. Vocalist M. Shadows revealed to Loudwire that the he was incredibly anxious during the process, and rightfully so.

"I was introduced to anxiety during this album. I had never had anything like that," the frontman revealed.

The singer admitted that on previous albums, he was the cracker of the whip, saying, "I'm kind of a slave-driver during the process, I keep pushing the guys to write more and more and more, and I'll throw out songs that people think are good. That's kind of the process we had for writing the music when Jimmy was around. We got to the point where we were really happy with the music and I was going to start writing the lyrics, and then Jimmy passed away."

Things then changed and he had to deal with a relatively new feeling and experience known as anxiety. He said, "I had a lot of anxiety and all these crazy things that I've never experienced before, and just trying to figure out what the perfect words was to say. We were in the studio with Mike Elizondo and everybody - brilliant artists and brilliant producers - but it was just kind of a crazy. It was a confined space and I just felt like we were in this hole, trying to dig ourselves out. When it was all said and done, it was definitely something we were all really proud of."

Watch Avenged Sevenfold's 'Nightmare' Video

Even with anxiety rapping at his chamber door, Shadows was proud of the end product. "I think on a musical level, I was happy with it, but not only that, I was happy with it on a sonic level, I think Mike did an amazing job and Andy Wallace did an amazing job, and when I got to sit back and listen to it all, I was just really proud of it," he said. "I was proud of all the work and struggle that we went through to get it done, I think it shows. It's definitely my favorite record sonically and emotionally that we've ever done."

As for the follow up? The band has further touring commitments and will sit down to ponder what's next once they wrap their overseas obligations.

Watch 'What Is Anxiety' Video

More From Noisecreep