What started out as a quiet evening at home last fall turned into a nightmare when Orianah Fast discovered an intruder in her Grand Forks, N.D., apartment.

She heard noises from her bedroom. Her two cats were hissing and running around, she said.

“It sounded like they were pulling pages from a comic book and jumping from wall to wall,” she said. When she investigated, the cats had knocked a bed pillow to the floor. One cat just stared at the pillow. Fast picked it up and found a coiled “ball python,” about 4 to 6 feet long.

“I jumped up, screaming at the top of my lungs and crying,” she said. “I wasn’t able to control my emotions.”

She ran for help, pounding on neighbors’ doors. Eventually, a man answered and came to her aid. He scooped the snake into a plastic bag and told Fast it was probably sleeping.

Like many Americans, Fast has a phobia that she can’t necessarily understand but that is nonetheless real. Whether it’s snakes or heights or an uneasy feeling when the elevator door closes, phobias can range from mildly embarrassing to completely debilitating.

Fast later learned that the snake, which belonged to her next-door neighbor, had escaped its cage and slithered through a heating vent system. Even though it was removed from her apartment, Fast was unable to sleep there for the next three nights.

“I was beyond creeped out,” she said. “I just couldn’t calm down. I just didn’t want to be there.”

When she did return, she moved the bedroom furniture so her bed would be further from the spot where she found the snake. That “deep fear” lingered for about three weeks, she said.

Since her “discovery,” when she enters the room, “I always look in that direction. But I tried to ignore it.”

Phobias may stem from something we have no memory of — rooted in “unconscious memory,” said Dr. Ric Ferraro, Chester Fritz Distinguished Professor of Psychology at the University of North Dakota.

“We have what’s called ‘infantile amnesia.’ When you ask someone what’s the earliest memory they can think of and ask their age [then], most people will say 3 or 4 years old. If someone tries to recall an earlier memory, even back to their birth, that’s a hazy area.”

Fear — like happiness — is an emotion we are born with, he said.

Childhood fears

Fast has no idea what caused her intense fear of snakes. Her earliest related memory is when, at age 7 or 8, she was walking with her mother near their rural home and they came across a snake.

“She picked it up, as though to teach me about it,” she said. “I freaked out. I don’t know what happened. I have no idea why I freaked out. It was only a garter snake.”

“Phobias typically affect us negatively,” said Ferraro. A fear rises to the level of phobia “when it starts to restrict behavior,” he added, “even to the point when it’s harmful to oneself.”

For example, he said, “if you’re afraid of water, you can probably drink it or bathe in it, but you may not swim for fear of drowning. If you fear the color red and you come to my office, and it’s painted red, you’ll have a very distinctive reaction: You may be sweating, you may have to sit down — much like PTSD [post-traumatic stress disorder]. In some cases, you don’t need the actual [fear] stimulus. For example, if war veterans [suffering from PTSD] hear a car backfire, they’ll respond accordingly.”

What’s in a number?

Some phobias are driven by superstition, such as fear of the number 13, he said. People with this fear may not drive on 13th Avenue.

“If something bad happens on the 13th, they attribute it to the date,” he said, as a way “to explain things they don’t understand.”

Phobias are often paired with something negative, he said. “It’s often tied to something that’s happened.

“If, as a child, you were bit by a German shepherd, you may be afraid of [that breed]. It’s an association that we’ve made. Even if the German shepherd is friendly, you’re still afraid.”

Among the several treatment approaches, “exposure therapy is very popular,” Ferraro said.

“If you were afraid of spiders, you’d be exposed to them gradually, in a piecemeal way. You might be given a picture of a spider, then see a spider in a cage. Somebody would hold out a spider for you to touch. It’s done incrementally.”