there is a public perception of large growth in nonstandard work times and work shifts.
In fact, these changes are probably more modest than is commonly believed. Regarding the lengths of shifts people work, the percentage of the workforce that works part time did increase between 1968 and 1996, but much of the increase occurred in the 1970s (Figure 2.2).
Evidence on changes from 1973 to 1991 in the distribution of work time throughout the day reveals two main findings (Hamermesh, 1996). First, the proportion of hours worked at night (between 12 am and 4 am) has decreased steadily over this period. At the same time, the proportion of hours worked at the "fringes" of the work day (6–7 a.m. and 4–6 p.m.) increased over this period. These trends are similar for men and women, although more pronounced for men.
Another aspect of timing is the extent to which work is concentrated at particular hours of the day. To study this question, Hamermesh calculated the proportion of total work time worked during the eight most frequently worked hours. The data indicate small changes from 1973 to 1985 and declines for both men