There are four bands with this name:

1) Sleepwalkers are a death doom metal duo from Austin Texas and Windsor, Ontario. Their debut demo "Hollowpath" was released digitally in May 2013. It can be obtained from http://sleepwalkersband.bandcamp.com.
http://www.facebook.com/sleepwalkersdoom

2) Hardcore band from Los Angeles.
http://www.facebook.com/pages/Sleep-Walkers/111809545524708

3) A post-hardcore band from Worcester, Massachusetts.
http://www.facebook.com/pages/Sleepwalkers/162123917147252

4) An electronic collaboration between Ben Marsden and Richard Siddall-Jones.
http://www.facebook.com/sleepwalkersmusic Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.