Working Irregular Hours Can Be Hazardous to Your Health, Psychologists Say : Jobs: Shift work can contribute to trouble sleeping, social isolation, even divorce rates. But it’s predicted that more and more people will work odd hours.

At a time when most people are preparing for work, a dozen men just off the night shift pull into the parking lot at the Roy Wilkens Recreation Center in Queens.

Inside the sunny gymnasium, they strip down to shorts and T-shirts and begin shooting layups, watched by Charles Coleman, a Trans World Airlines maintenance worker who founded the basketball league for shift workers three years ago.

“Shift workers don’t have a chance to play organized activities,” said Coleman, who recruited corrections officers, postal employees and airline workers at Kennedy International Airport. “It’s hard to adjust.”

The social isolation Coleman speaks of is just one problem shift workers face, psychologists and occupational health experts say.

Studies show that up to 80% have trouble sleeping. Over time, sleep loss combined with other strains from irregular hours can affect health and job performance. In the case of a trucker or nuclear power plant operator, the results can be deadly.

Yet more and more people are working unconventional hours, the Bureau of Labor Statistics says.

More than 20 million Americans work other than daytime hours. The length of the shifts and time of day vary, from consistent nights to rotating schedules.

And the number of shift workers is expected to grow as advances in computers, telecommunications and transportation bind the U.S. economy ever closer to markets in different time zones.

“The way society is going, people want to have different services available around the clock,” said David Liskowsky, project director of a recent report on shift work by the congressional Office of Technology Assessment.

The OTA didn’t measure the toll on society, but The Wall Street Journal has estimated that shift work costs companies $70 billion a year in lost productivity, medical bills and industrial accidents.

Shift workers are more likely to suffer from digestive disorders, heart disease and emotional problems. Some research suggests women are at slightly higher risk of miscarriage.

“Quite a sizable proportion of shift workers are falling asleep at work or on the way home from work,” said University of Pittsburgh psychologist Timothy H. Monk.

“After a while, your friends lose contact with you. There’s a higher incidence of divorces and juvenile delinquency,” said John Zalusky, head of the office of wages and industrial relations at the AFL-CIO in Washington.

Researchers say that shift work disrupts the body’s circadian rhythms--the 24-hour cycles cued to light and darkness that regulate everything from heart rate and hormones to digestion and alertness.

Daytime sleepers, who often complain of noise and other distractions, may be waking up prematurely simply because their body temperatures are rising from an early morning low.

“Sleep deprivation is a bigger problem than drugs in the workplace,” said Marty Klein, a psychologist who runs SynchroTech, a Lincoln, Neb., shift work consulting firm.

However, 15% to 20% of shift workers prefer their unconventional hours, he added. “They’re psychologically different. They’re night owls.”

Some like the solitude and relative lack of supervision, others the chance to go to school, run errands when everyone else is at work or spend time with their children.

In half of all young couples with children under 5, at least one parent is a shift worker, the government says. And shift work pays a little better, up to 10% more in the United States.

But most people who work irregular hours do so because it’s required or they can’t get another job. And increasingly, biological research holds the key to their woes.

Occupational health experts now believe workers are better off rotating from days to evenings to nights because biologically, it’s easier for people to go to bed later than earlier. For years, the standard has been the reverse.

Many companies are adopting 12-hour schedules, in which workers trade longer hours for more days off on the theory that the body has more time to recuperate.

The Raritan River Steel Co., a round-the-clock operation in Perth Amboy, N.J., began phasing out eight-hour shifts in 1988. Today, 290 of the 300 hourly workers in the non-union shop work 12 hours at a stretch.

“Everybody is very pleased with it,” said Bob Pepe, director of human resources. “There’s less absenteeism and our safety record has improved.”

The schedule was designed by Richard M. Coleman of Ross, Calif., one of a growing number of shift work consultants hired by companies to boost productivity and cut down on employee error.

“We have schedules where the employee never works more than two to three days in a row,” Coleman said. “Over the year, they have 182 days off compared to the average worker, who has 104 days off.”

But the growing popularity of 12-hour shifts has met resistance from labor unions and other occupational health experts, who note that eight hours is the basis for federal standards for exposure to toxic substances in the workplace.

Some companies are turning to lights to reset workers’ internal clocks--a technique used in 1990 to help astronauts prepare for shuttle missions. The astronauts’ exposure to light was closely controlled, and they reported sleeping more soundly during the day.

The cost of installing bright lights and related equipment can cost a factory more than $100,000, said Nat Mass of Light Sciences Inc. in Braintree, Mass. But he believes bright lights are the most powerful solution for keeping workers alert.

“Even workers working six days on the night shift don’t show any physiological adaptation,” he said. “They are chemically out of synch at every point in time and are reaching their peak biological alertness while trying to sleep.”

Shift workers can do a lot on their own to improve their adjustment once they have a basic understanding of biological rhythms, experts say.

“The problem is, people don’t perceive shift work as a lifestyle,” said psychologist Klein. “They try to lead their lives as normal day people do and are constantly reverting to day habits.”

Shift work in some nations is controlled by laws and collective bargaining agreements; of 49 countries reviewed in the OTA report, the United States was one of just six that don’t regulate shift work, except for transportation and the nuclear power industries.

Some countries mandate special food arrangements. France gives shift workers money to soundproof their homes and provides for the rebroadcast of certain television shows. Australian night workers earn an extra week of vacation every year.

But legislation to regulate shift work in the United States may be premature because basic research is lacking, experts say.

Four years ago, health officials in New York limited the on-duty hours of emergency room physicians after a young woman died soon after being admitted to a hospital.

Two doctors who treated her had worked 18 hours. A grand jury recommended the regulations, which are expected to cost the state $3.1 billion over the next 10 years.

Yet the restrictions may not be the right answer, said David Dinges, a University of Pennsylvania psychologist.

“They applied a simple model that the longer you work, the worse it is,” he said. “If you’d asked scientists, they may well have offered alternative suggestions, like anchor naps.”