While the Olympic Games mean medals for American athletes, they also may present Olympic-size headaches for American employers.

A recent poll by Marist Institute for Public Opinion found that 80 percent of adults will tune in at times to the Olympic Games in London. A survey issued by Velti estimates that about 40 percent of all adults will stream at least a portion of the games on mobile devices. Of consequence to employers is that, due to varying time zones, many of the Olympics’ premier events and finals — all being streamed live — occur during the daytime hours in the United States, when many employees are on the job.