Doreen Cloherty, a cardiac intensive care nurse at Beth Israel Deaconess Medical Center in Boston, has an ordinary life. She has a steady job doing what she loves, she tries to get to the gym every week, and she has plans to marry this June. But her work schedule would drive most people crazy: On any given weekday, she might work from 7 o'clock in the morning to 7 o'clock at night, or 7 a.m. to three in the afternoon, or 3 p.m. to midnight. Some weeks she works three twelve-hour shifts, other weeks she works three twelves and an eight. Every third Saturday and Sunday, she is on the job, as she puts it, "7a to 7p," and every sixth weekend, "7p to 7a." It is a schedule that is exhausting just to contemplate.

As modern life increasingly runs on a 24-hour-a-day, seven-day-a-week basis, Doreen Cloherty's experience, while extreme, is not unique. Today, one-third of full-time working Americans toil away on "nonstandard" schedules. They put in the bulk of their work effort at times other than the usual 9 a.m. to 5 p.m., Monday through Friday.

For the individual family, coordinating everyone's schedule is the stuff of everyday life how to manage work, get the kids to soccer, pick up groceries, take the car to the repair shop, and still find time to spend with friends and family. Economywide, it's a huge exercise in social scheduling that determines when we work, play, and sleep. The outcome - the patterns in working hours that we observe - reflects the interaction of employer needs with employee preferences. It also reflects other people and their schedules - our family, friends, and coworkers. Sometimes, it's an advantage to be doing things at the same time as everybody else; at other times, it's useful to be on a different timetable.

BUYING BETTER HOURS

About one-third of full-time American workers are on a nonstandard schedule, says University of Maryland researcher Harriet Presser. Almost one-fifth regularly work some weekends; 10 percent spend at least half their regular "day" after 4 p.m.; and 7 percent work irregular schedules or rotating shifts. Part-timers are more likely to work nonstandard schedules than full-timers. Even at 3 o'clock in the morning, at least 5 percent of women and 7 percent of men are engaged in market work.

Men and women are about equally likely to work a nonstandard schedule, but particular times and occupations differ. Men tend to work nights or rotating shifts, with cooks having the highest chance of odd hours. Women with nonstandard schedules tend to work as nurses, cashiers, and waitresses. Nonstandard schedules are least common for engineers, teachers, and secretaries, and more common among African-Americans and the less educated.

Still, looked at another way, these figures mean that two-thirds of us work regular weekday gigs. And this is probably no accident, for we are daytime creatures, biologically and psychologically geared for daylight activity. Body temperature is lowest at about 5 a.m., and melatonin, which makes us feel sleepy, begins to increase after 10 o'clock at night. Scientists at Cornell University recently reported that they were able to reset a person's biological clock by shining a bright light on the back of the knees, suggesting a more complex physiological basis for circadian rhythms than had previously been supposed.

Before the invention of artificial lighting, this was not an issue Daylight was needed for most activity, so we tended to begin our day at sunrise and sleep after sunset. As production and other economic activity expanded into darkness, our biological clocks underwent stress. Many people do not function well at night. Some report having a hard time eating, others can never adjust to sleeping during the day. Said one supervisor of her stint on an evening shift, "It was horrible. 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. Also, observers have speculated that the shift premium for low-skilled workers may be shrinking, reflecting the conditions that have depressed wages in that part of the labor market.

Still, late-night (as opposed to evening) work has declined over the past twenty years in the United States, according to University of Texas economist Dan Hamermesh. Some of the drop may be due to technological change or the decline in jobs in manufacturing. Many manufacturing processes use machinery that cannot be turned off or is too costly to lie idle, encouraging a third shift.

But Hamermesh believes that a reduction in overnight work primarily results from rising education and affluence. The incidence of overnight work is low among better-educated workers. It has declined most for the upper quartile of the income distribution. The self-employed, who have some control over their schedules, though more likely to work weekends, are less likely than company employees to be on the job after 10 p.m. By contrast, night work is performed disproportionately by minorities, the newly employed, and those with relatively little human capital. All this suggests that workers "use part of their ability to obtain additional earnings to purchase more attractive work times." Those of us who can afford better hours choose not to work the graveyard shift.

Doreen Cloherty is thus something of an exception. Highly trained and paid, she likes the intensity and demanding pace of cardiac intensive care. She has wanted to be a nurse since first grade and has worked in hospitals since high school, so she knew exactly what she was getting into. Her fiancé's work schedule also helps He travels for his job as an engineer and understands her demanding timetable. And, there are advantages to being on a different schedule from the rest of the world She can make a dentist appointment at the last minute, shop and go out to dinner when places are less crowded, and stop by her parents' house for coffee and a quick visit midmorning. Still, when you ask her about whether she plans to continue her schedule in the future, Doreen sighs and says wistfully, "For now, it's good."

THE WORKDAY SPREADS OUT

At the same time that rising affluence has reduced overnight work, it has also increased the demand for goods and especially services at the edges of the standard workday and on weekends. Working women, dual-career families, and growing incomes have all contributed to this trend. For department stores, evenings and Saturdays have long been peak sales times; now malls have extended normal shopping hours until 9 p.m. or later, and many stores are open on Sundays. Aided by technology, we ship packages for next-day delivery and order merchandise at all hours via telephone. Even "banker's hours" may become an anachronism, as 24-hour a-day service proliferates and some banks, such as BankBoston, keep supermarket locations and certain retail branches open until 9 o'clock at night and on Sundays.

Although the bulk of customer demand is around the edges of the workday, the evolution to around-the-clock service can be a relatively easy next step. Supermarkets and other retail establishments that clean and restock overnight, for example, can add a small staff to service customers at little additional expense, while the extra hours reduce the strains and congestion that would otherwise occur on Saturday afternoons. And for other firms, providing maximum convenience to the customer is a fundamental part of the business.

MANAGING AROUND THE CLOCK

Fidelity Investments has offered retail customers a chance to make trades and ask questions 24 hours a day, seven days a week, for eleven years. Although the bulk of calls come in during market hours, both the 3 p.m. swing shift and the 8 p.m. to 6 a.m. graveyard shift provide a key service to customers who prefer to call at those times, observes Senior Vice President Scott Gygi. Gygi, who runs the 24-hour phone center in Salt Lake City, Utah, says managing an around-the-clock operation involves balancing the interests of the company with those of its staff.

Despite paying a shift premium, Fidelity is not unusual in that it often has more night slots available than employees want. Gygi estimates that about 80 percent of his staff of 850 get their first choice of shift. As in many firms, seniority matters. New employees often must take an overnight schedule, then wait their turn. "Our scale helps us," he notes, "letting people move around as their needs change." In other firms (many hospitals, for example), evening and night shifts are split among the daytime staff to spread the pain.

Fidelity's graveyard-shift schedule of four ten-hour days is also a compromise; on pure efficiency grounds, a five-day week would probably be better. But the four-day week allows employees an important extra day to recover, as many try to live in sync with the rest of the world on their "weekend." It also reduces the fixed costs of commuting and arranging child care. Fidelity is able to economize in other ways, such as having graveyard-shift workers share desks with daytimers.

One of the big challenges is helping Fidelity's night staff feel a part of things. Care is taken to ensure that they receive the same communications and opportunities as their daytime counterparts. Management meetings are scheduled for late afternoon so that supervisors from all shifts can attend with minimum inconvenience. And procedures for employee evaluations and promotions need special attention. "Visibility is always a problem," observes Gygi. So, senior officials in Salt Lake City, including Gygi himself, occasionally work late to stay in touch. And certain performance measures are assessed differently for graveyard-shift workers because the night-call mix differs.

One measure of Fidelity's success in managing its 24-hour center is the longer tenure of the graveyard-shift staff. Their greater experience is especially valuable as overnighters must supply a wider range of competence than during the daytime, when specialists are available. And evening and night work may raise output in other ways. "It focuses the mind," observes a supervisor from another company. "There are no distractions, no shopping, no doctor's appointments."

AGAINST THE TIDE

Although the majority prefer a standard schedule, working at odd hours holds advantages for some. For night owls, the camaraderie and atmosphere of the world at night can be seductive. "You develop an 'us versus them' mentality," notes chef Moncef Meddeb. "When people who work days complain about being tired, you think, 'What do they know about being tired?'"As the creator of L'Espalier, one of Boston's premier restaurants, Meddeb lived a fast-paced, sometimes glamorous existence - in the kitchen until 1100 every night, and to bed even later. He hobnobbed with famous chefs and traveled around the country making guest cooking appearances. "I didn't choose the lifestyle consciously," says Meddeb, who grew up in Paris and Tunisia. "People just told me I had talent. I was foolish enough to believe them!" But Meddeb thinks he made the choice subconsciously. "I had the personality, the need for sheer energy release that you get running a restaurant. The atmosphere in a kitchen is full of joking. You say things you never could in another environment." He also notes that odd hours are the lot of any entrepreneur. "Once you start your own business, you really have no choice but to work all the time. But with a family, it is very difficult." Meddeb now eats dinner at home with his daughter most evenings and runs a lunch-time place in Boston. He spends only a few nights a week at Aigo Bistro, his Concord, Massachusetts, restaurant.

For others who work nonstandard schedules, family responsibilities are the primary motive. Diane Murphy, originally an education major, switched to nursing precisely because she wanted a career with flexibility for child care. She and husband Ted, a Boston police officer, have been a "split shift" couple for sixteen years. For nine of them, Ted worked 3 p.m. to 11 p.m. and Diane worked 11 p.m. to 7 a.m. (and every other weekend). When Ted was promoted and had to work nights, Diane switched to days. "It can get pretty crazy," Murphy recalls. "Sometimes, Ted would have to pile the kids in the car and meet me at work to hand them off."

The good part "We have never had to pay for child care and our kids have never been latch-key children," says Diane. Her schedule has allowed her to coach softball and ferry her son to hockey. And Ted, like many split shift fathers, has spent more time with his children and on household chores. But split-shift arrangements can take a toll, stressing even the best marriages and making strangers out of family members. Socializing can be difficult. Diane often attends family functions without her husband. Thus, most couples prefer to work at the same time, if they can manage it, and many switch to standard hours as soon as they are able.

For certain families, the benefits of a nonstandard schedule are mostly financial. Working at odd hours can provide a way for low-skilled or inexperienced workers to get their first job. Shift premiums can raise earnings substantially above what they would be otherwise. Economist Peter Kostiuk observes that, in many instances, "workers with low potential daytime earnings choose to work nights to increase their earnings."

But this can put low-skilled single parents in a bind. Much of the projected job growth is expected in occupations that require evening and weekend work, such as cashiers and restaurant workers. At the same time, the long-term trend toward greater female labor force participation has left fewer family members able to help with child care. Institutional child care centers that operate around the clock are rare and typically too expensive for low-income workers. And in-home care is hard to find during odd hours. At nights and on weekends, most providers are busy caring for their own families.

NO ONE IS AN ISLAND

Each of us tries to schedule our work and other activities to suit our individual circumstances, but no one performs this juggling act in isolation. Most decisions depend not only on one's own desires, but also on the schedules and preferences of the people and companies with whom we interact. We choose when we want to work not in the world as we might want it arranged, but in the world as it is.

Swimming against the tide can have advantages, not only for people who can care for their children or shop when stores are empty, but also for communities that are able to relieve congestion on shared public services. So consulting firm Arthur D. Little, in a planned move to Weston, Massachusetts, has assured Weston officials that given the odd hours its staff works, the firm would place less stress on roads than other users of the site.

Still, it is generally more productive to work at the same time, and more fun to play at the same time Hence, the predominance of the standard day, especially among the affluent and best educated. For those who choose otherwise, working odd hours may be a second-best solution.