10.1 The Problem of Stress 383 particularly true if the direction of the rotation is from day to night to evening (as opposed to day to evening to night).Rotating shifts lead to sleep disturbances,which in turn are associated with medical (e.g.,gastrointestinal)and psychological (e.g,anxiety and depres- sion)difficulties.Rotating shifts also seem to be particularly hard on older workers andy.1989). Moreover,the biological clock is not the only potential challenge to adjusting to shift work.Monk.Folkard,and Wedderburn (1996)found that daytime social obligations such as family,community,or church activities can throw off circadian rhythms for night-shift workers.In addition.Monk and Wagner (1989)found that even when night-shift workers have begun to adjust their circadian docks with careful attention to guidelines for sleeping during hours off,these types of daytime activities can have negative effects that far out. weigh improvements resulting from gradually adjusting the biological clock. Shift work is more common in some occupational groups than others.Nurses,blue. collar workers,and public safety personnel have higher concentrations of shift workers than professional,managerial,or white-collar groups (Smith et al,1999).The most frequently studied of those occupations is the nursing profession.Barton(1994)examined the differ. ences between nurses who chose to work the night shift on a permanent basis and nurses who were assigned to rotating night shifts.Permanent night-shift nurses reported signifi. cantly fewer problems with health,sleep,and social or domestic activities.This was particu- larly true for individual nurses who chose to work on the permanent night shift compared with nurses who chose to work on a rotating-shift schedule.The most important reasons the nurses in this study gave for choosing the permanent night shift were that night-shift work permitted them to more easily fulfill domestic responsibilities and that it paid better. Thus,for those who chose permanent night work.doing so actually improved control and scheduling of work-non-work roles.But the nurses on a rotating-shift schedule felt that their lives were disrupted every time they had to work afternoon or night shifts.It appears that permanent night-shift work provides a significant opportunity for establishing a work- life balance that is not possible with rotating shifts or,in some circumstances,day or after. noon shifts.This seems to be particularly true of dual-wage-earning families with young children.In another study of nurses,Bohle and Tilley(1998)found that the level of work- non-work conflict was one of the strongest predictors of satisfaction with shift work. Flexible and Compressed Workweek Schedules Shift work.regardless of whether it is fixed or rotating.defines the work schedule rigidly.In general,shift workers are expected to work eight hours per day.five days per week.But there are other scheduling variations that are not so rigid. Rextime Individual workers who are given discretion over the time they report to work and the time they leave work on a given day are working a flextime schedule.Such schedules are uncom- mon in manufacturing organizations because the interdependence among workers in h水a打探 assembly-line and continuous-process operations makes the absence of a particular worker given discretion over the meh与port to work and problematic (Baltes et al.,1999).A survey of organizations in 2009 revealed that 44 percent he time they leave work o的 of them permitted some form of a flexible workday (Society for Human Resources Management,2009).In a typical flexible work schedule,every worker is expected to be at work during a core"period (e.g.10:00 a.m.to 3.00 p.m.)but is permitted to arrive as early as 7:00 am.or leave as late as 9.00 p.m.(Baltes et al,1999).Regardless of when they arrive and leave,they are expected to be at the workplace for 40 hours a week.In some organiza- tions,the individual is also required to be at work 8 hours each day,whereas in other organ- izations,the individual is still expected to be at work for 40 hours a week but is permitted to