A graveyard slot (or death slot) is a time period in which a television audience is very small compared to other times of the day, and therefore broadcast programming is considered far less important. Graveyard slots are usually in the early morning hours of each day, when most people are asleep. Because there is little likelihood of having a substantial viewing audience during this time period, providing useful television programming during this time is usually considered unimportant; some broadcast stations go off the air during these hours, and some audience measurement systems do not collect measurements for these periods. Some broadcasters may do engineering work at this time. Others use broadcast automation to pass-through network feeds unattended, with no one outside of broadcasting