On November 3, we all went through the familiar ritual of changing our clocks back an hour at the end of daylight saving time. Originally introduced to reduce energy consumption during World War I, DST (which is when clocks are ahead an hour-when it gets darker later-during the summer) potentially affects things far beyond how light it is when we get up. TV-watching patterns, crime rates, and our drinking habits could all be altered by this twice-annual change.