There are at least three artists that have performed under the name Big Sleep: (1) An Irish-Italian group based out of Dublin, Ireland; (2) American/German singer-songwriter Stefan Schwerdtfeger; and (3) a 1970s band from Wales.
These are photos from concerts where Big Sleep played, so they may be of other bands that played the concert as well.
The Big Spill Music Festival 2012 Mar 13, 2012 San Antonio, Texas, United States Uploaded by Impeachman