Continued dramatic twists in the Persian Gulf war could make it harder for Americans to cope with a lengthy conflict, psychologists say.

Such events, along with fears of domestic terrorism, interfere with the process of settling into a sense of business as usual, they say.Nobody knows precisely how Americans would react over the long term to extended fighting in the gulf, several experts cautioned. But the majority of people who do not have a friend or relative in the war should be able to handle their concern without psychological problems, they said.

"Most people are not going to have sleepless nights. Most people's appetites are not going to be affected," said Milton Schwebel of Rutgers University, who is a senior research scholar with the Harvard-affiliated Center for Psychological Studies in the Nuclear Age.

After dealing with crises like wars for an extended period, populations tend to get used to them to some degree and conduct business as usual despite their concern, a process called habituation.

The American public hasn't gotten there yet, suggested Philip Levendusky, director of the cognitive therapy unit at McLean Hospital in Belmont, Mass.

Instead, he said, people are in an uncomfortable "gray zone," not able to classify the war as either the very quick operation some had hoped for or a long haul like Vietnam or World War II.

The uncertainty is fueling anxieties in the population over such things as domestic terrorism, said Levendusky, who noted that at least five people approached him with concern last week about his plans to travel by air.

A terrorist attack in the United States would block habituation, he said. But if no such attack occurred, he expected public anxiety to peak over the next few weeks and then subside as habituation sets in.

At that point, he expects dissent about the war may increase if troops do not appear to be making substantial headway, because people's concerns will shift to such matters as the cost of the war.

But Schwebel said habituation seems "rather unlikely, I think, for the foreseeable future."

The gulf war is providing a steady diet of exciting or disturbing news against a background of uncertainty.

"It's difficult to become used to it, habituated to it, because there's too much excitement, too much anticipation, too much of the unknown," he said. In contrast, Vietnam and World War II were marked by long respites of relative inactivity, he said.

Many people will be distracted and upset by the intrusions of dramatic war news, he said, but only a small percentage will go on to suffer symptoms such as sleeping difficulties, disrupted appetites, sadness, rage, insecurity or depression.