question: How much less , on average , do workers in the U.S. sleep on Mondays after switching to DST , according to the 2009 study ?
answer: 40 minutes
turker_answer: Workers in the U.S. sleep 40 minutes less on Mondays after switching to DST , according to the 2009 study .
rule-based: 40 minutes do workers in the U.S. sleep on Mondays after switching to DST , according to the 2009 study .