About 200 Twin Cities residents rallied Saturday in support of fair and humane treatment of the night people — the almost invisible people who toil at night, cleaning retail stores and office buildings. The cleaning of the major retail stores is contracted to a company responsible for the treatment of the cleaners. But workers have suffered increased abuses, ranging from outright slavery to reduced wages, lack of air conditioning or heating. Centro de Trabajadores Unidos en la Lucha (CTUL, or in English, the Center for Workers United in Struggle) began in 2007 as a project of the Worker’s Interfaith Network. Saturday’s 3.6-mile march was directed at Lunds, Super Valu and Target. Super Valu was designated as the primary target for further pressure to improve wages and working conditions.