Many people do not function well at night. Some report having a hard time eating, others can never adjust to sleeping during the day. I was tired all the time. I became obsessed with sleep. The impact goes beyond unpleasantness or inconvenience.
Some managers report increased illness, especially more colds and flu in the winter.
And a wealth of studies shows that both accident and productivity rates worsen at night and that night jobs impose added health risks. To compensate and attract additional workers, many firms pay a shift premium for evening and nighttime jobs. Presumably, this premium is set just high enough to entice the workers necessary to meet the firm's demand. Using 1985 data, economist Peter Kostiuk estimated that the average shift premium was about 8 percent. More recent anecdotal evidence suggests that, for some firms, the current premium may be about 10 percent for evening work, a couple of percentage points more for overnight.