The nightmare struck without warning. One moment, Sandra Ogle was her usual self: “The healthy-as-a-horse kind of person,” she recalls. “Never been sick at all.”

A moment later, the Napa photographer “flopped down in a chair — and I was gone for weeks. I lost the ability to know where I was.”

Ogle spent the next several weeks in the intensive care unit at Queen of the Valley Medical Center. She credits her doctors and hospital staff with helping to pull her through the frightening symptoms caused by her dissected aorta.

But the medication she received gave her a different view of the staff at the time.

“I thought these were space aliens coming to get me — I was on such a trip. I consider myself fairly emotionally fine, and this was just terrible: I was absolutely, totally, completely convinced that these people — whoever they were  — were going to kidnap me and my granddaughter.

“I really had no concept of what was real and not real.”

Some of Ogle’s hallucinations were “goofy,” she recalls. “For a while I thought I was Mrs. Roosevelt. We went on train trips and had these receptions; I entertained people.”

But for the most part, her nightmares were scary and bizarre.

“They had to put a breathing tube in,” Ogle said. “I was convinced that that was their attempt to kill me. There was no question that I believed it.”

After about a month in the ICU, Ogle spent weeks more at the Queen before she was well enough to come home — back in her senses, but haunted by the hallucinations that had tormented her for so long.

‘Me, but not me’

As she recovered, Ogle began to make photographs in an effort to express what she had been through on her hellish journey away from sanity.

Her collection of old-fashioned dolls provided her with the perfect metaphor: “They’re really kind of frightening,” she explains. “They were me but not me … just close enough that 99 percent of people who look at the picture know that’s supposed to be me, but it’s dehumanized.”

Ogle shot the dolls in colored light to express her emotions, often with Expressionist shadows to heighten the nightmarish effect.

In the photo “Suspended,” one doll dangles forlornly from an electric cord embedded in its back; its face is hidden, its limbs hanging inertly. In “Falling,” the doll appears to be plunging from a high ladder; “Indignity” dumps it headfirst into a metal cylinder, with only its skirts and button boots poking out.

 “It was kind of a cathartic thing,” Ogle says of the series of 15 photographs, now collected in a book called “The Dark: A Photo Essay.”

“I thought it was just an interesting way to deal with this and explain to people what happened and how I felt.”

While posing one of the dolls, Ogle accidentally broke its porcelain head into pieces — leading to powerful images of dysfunction including “Broken” and “Addlepated.”

“I couldn’t have broken it on purpose and had it work out better,” she says.

Ogle emphasizes that the series is not aimed at the staff at the Queen, writing in an afterword to the book that “I completely recognize, now, that those professionals saved me.”

“The Dark” has a few words of text for each photograph. For “Broken,” she writes simply, “Wellness is broken. Sanity explodes.”

But Ogle wants viewers to concentrate on the images first.

The words are there, she says, “just enough to tell them, if they really wanted to know, where my brain was at the time — but not enough to sway them into feeling the same way.”

Ogle created the photos for “nobody but myself,” yet has found that many people recognize something in her work.

“Even though they didn’t have the same experience, they certainly had the same emotion,” she says.

“The Dark: A Photo Essay” is available in a signed, numbered limited-edition hardback for $70 at Ogle’s Studio II Gallery, 570 Soscol Ave. in Napa. Framed prints from the series are $400.