When Dr. Renata de Arboleda first came to the Canal Zone as the resident psychiatrist 13 years ago things were still pretty calm. Life was good, easy, fun. People still had a sense of purpose.

Arboleda, who is of Austrian origin enjoyed the calm of Zone life after working in a New Jersey clinic where pressure was greater.

But by 1973, when talk of the treaties began appearing in the local Panamanian papers, symptoms of stress began developing among the Zonians. Ronata de Arboleda, 53, was not exempt.

She doesn't mind talking about it, needs to talk about it in fact. And these days she's got plenty of time. At her little wooden outpost of a clinic, located near the edge of the jungle in the Zone. "We get less patients because the problems are not those they can do anything about," she says.

"When there is a real environment stress, people don't have time to worry about smaller things. I'm talking about the typically neurotic person, who has a lot of time to ponder himself.

When there's a lot of real stress, mental illness goes down. And," she says, "there is a lot of real stress here. You want to know about stress? I'll tell you about stress," she says, her voice rising.

The first stress five years ago was not knowing. The insecurity, the headlines increasing, the image carefully created for us of gravy trains, manicured lawns, a colonial existance, a slavemaster mentality.

Now we are getting a lot of divorces and also quick marriages. It's the I've got to start absolutely new' syndrome. This whole treaties business is the precipitating cause for people to look at their lives and make radical changes."

As Dr. de Arboleda continues talking she becomes increasingly agitated; her long thin arms and legs are constantly in motion; her Viennese accent becomes thicker and she smiles nervously.

"If one has to drastically alter one's life situation," she says, "then why not topple the whole thing?

"When I came here 13 years ago it was so different. You say now, 'Oh my God, it's all going down the drain.' We don't know what the treaty implementation means. So how can one expect people to go on with the show until the curtain comes down when there's no applause?"

At the Balboa Beauty Salon in the Canal Zone the hairdressers are worried.

They are worried because many women in the Zone are coming in to have the color of their hair changed almost every week. Red one week, black the next, blond the next . . . Now many women find their hair is falling out.

Renata de Arboleda has a theory about this. She calls it the "rat displacement reaction." A scientist, she says, came up with the Rat D.R. theory after watching rats fight during mating time. He would take the winning rat from a group of tiny ones and the winning rat from a group of huge ones.

"Then" says Renata, "he would put the tiny one in with the big one. The tiny one would look up at the big guy and immediately start cleaning his whiskers.

Here in the Zone, she explains, people's lifes are about to be obliterated. "For many people this is home. Theyhave no place to go. When people say 'Whar are you going?" 'I have no forwarding address.' They can't allow themselves to think about it. So they are grooming their whiskers." Pretending everything is normal.

"When I first came here to the Zone 13 years ago," says de Arboleda, "I was horrified at the tight regimentation of my life, the 24-hour duty, don't attract attention, go straight and narrow, don't cause incidents. At first I said, 'My God,' is worse than Russia. Every time you go to the grocery store you have to flash a number. But after two years I took to it like a fish takes to water.

"People take to the work here. The common purpose is very uniting. I made friends, I fit in. People get a great joy out of working for a cause, the Canal. Call it dedication. I never encountered it before. Ther is no private enterprise. We don't even have a paper of our own. We have a public information paper."

This was soothing, according to de Arboleda. Anti-stress. She married a Zonian and though she was Austrian, she became more American than the Americans in the Zone. More Zonian than any of them. She becomes a spokesperson for Zone problems and the Zonians themselves. The greatest advocate of their way of life.

"Think of it," she says with a laugh. "If the director of a hospital anywhere else lived in the kind of house I do, well . . . they would think I was crazy!

"Here," she says, "you don't keep up with the Joneses. There is not status. You can drive an old car, dress the way you want. You can do away with the outward sham.

"We don't have the dog-eat ambitions, the push and pull. You get hooked. I don't know how to describe it. I was the last person who could have adjusted to a benign military dictatorship which we have. I realized this was an experiment in socialized society. And it works.

"And we have an island of sanity. No crime. It may be old-fashioned but you word, you enjoy yourself, you have interests, you don't have the police. The police are the caretakers of the community."

But now she says, "The purpose is destroyed. People become entirely individual. They say, 'What's going toe become entirely individual. They say, 'What's going to happen to me?' We're like ordinary American citizens.

"It will soon he," she says, "that when someone says I lived in the Canal Zone people will say, 'What's that?'"