Sandra Bernhard doesn’t light up a room, she takes it over. Maybe even holds it captive for a while.

But her presence isn’t nearly as overpowering in the apartment she sublets in New York City’s Greenwich Village. Especially when she answers the door dressed only in a plaid flannel robe.

Inside, Bernhard sits in a dining-room chair and stares out a window overlooking Sixth Avenue traffic as a stylist applies makeup for a photo session. She is very much at home, even though her real home is North Hollywood, Calif.

She is relaxed, friendly — sweet, actually — not at all the dominatrix whose aggressive approach to humor has teased and taunted off-Broadway audiences and talk-show hosts, real (David Letterman) and imagined (Jerry Langford, Jerry Lewis’ character in The King of Comedy).

“I’m a control person,” says Bernhard, 32. “Very much so. It’s hard for me to relinquish my power.”

Bernhard concedes that her domineering ways have taken a toll on her friendships. “It makes it tough on me, too, because I can’t let people take care of me. It makes (relationships) difficult,” she says. When she is working, whether it be a guest spot on Letterman or starring in her one-woman show off-Broadway, Without You I’m Nothing, Bernhard comes across as tougher than the leather jackets that are a staple in her predominantly black wardrobe. Her humor is sometimes so caustic it could eat through pipe, but it has always masked a longing to be liked, a sensitivity as prominent as her jutting jaw, huge honker and Rocky Horror lips.

Sure, Bernhard is sarcastic — that is her bread-and-butter pitch. She is also smart, sharp and, in a weird, wonderful way, sexy.

But pretty? “No, I don’t consider myself pretty,” she says. “I don’t think that is a flattering word. Pretty means something helpless, something unattainable and unreachable, and I don’t think I’m that way. I think I’m sensual. I’m more beautiful than I am pretty. Pretty is a high school cheerleader.”

Yet pretty pops up in the title of her first book, Confessions of a Pretty Lady, to be published this summer by Harper & Row. Confessions is a collection of autobiographical sketches, more intimate than funny, that expose Bernhard’s softer side. She hopes the book will dispel what she feels is the public’s biggest misconception about her: “that I’m not vulnerable.”

Imagine that. Beneath the strutting wild woman with the biker’s charm hides a person who, she says, is basically sad.

“Yeah, I think I have Sylvia Plath elements,” she says, “a serious manic- depressive, a little Bell Jar action. I have my moments. I get tired of being sarcastic. People think I’m always sarcastic. I try to go off in different ways being funny, but sarcasm is easy for me.” It is the easiest way to make people laugh, she says. “Being sarcastic or being wild — really wild. Actually, I like that better.”

Bernhard first endeared herself to the masses in 1983 by performing something of a public service: She bound and gagged Jerry Lewis in Martin Scorsese’s The King of Comedy. “It was a great way to enter people’s consciousness,” says Bernhard, who was named Best Supporting Actress by the National Society of Film Critics. “I just thought the film was one of those classic films because it made a really important statement about the media. It was way ahead of its time. It was making statements that people weren’t ready to hear. Now, in retrospect, I think a lot of people have changed.”

Except for a cameo in a Muppet movie, Bernhard has not appeared in another film until now: She plays a kinky nurse in Track 29 (opening nationwide July 8), starring Theresa Russell.

But Bernhard hasn’t been low-profile. In addition to developing her “one- woman show of pop-culture catharsis,” Bernhard has gained notoriety for her frequent appearances — 20 at last count — on Late Night with David Letterman.

“What do I like best about doing it? Just the fact that you can get away with almost anything,” she says. “There’s no real confinement.”

Letterman routinely uses that freedom to his advantage, but he is definitely on the defensive with Bernhard, who obviously delights in making the host cringe at her off-the-wall candor and make-believe tales of their sexual romps.

“I disarm him,” she says. “He can’t be condescending with me the way he is with most people. He knows he is not dealing with a typical actress. He respects me, but at the same time I kind of freak him out a little bit.”

A little bit? Letterman all but abandons ship every time Bernhard walks out. During one show last year she wore a leather bustier (so named because, she told Letterman, “it boosts your ‘yays”‘) and said the boom mike hovering above the set was reminiscent of the nights Letterman looks down at her from a stepladder in the bedroom (“Not if you live to be a hundred,” Letterman retorted).

Bernhard may be imaginative and adventurous, but she drives a Honda Accord and likes Bon Jovi, Prince and mid-’70s disco. “I like a lot of stuff from that era,” she says. “It was really fun, before everything got a little dark and depressing. People went out and had a good time. They weren’t afraid.”

Bernhard learned at an early age the crucial, hidden advantage of being funny. “I knew how to make people laugh to manipulate them,” says Bernhard, quick to add that she is not easily manipulated.

“I’m not the type that gets into something and drops my own persona. I’m more of an observer and a commentator.”

And when it comes to recreational drugs she has a bit of Nancy Reagan in her. “That’s the first way to turn me off,” Bernhard says. “When people try to give me drugs or something, it’s like, ‘Get out of my face.’ It’s sloppy, it’s ugly and it’s inexcusable behavior.

“As my friends will attest, since high school I’ve been vehemently anti-drug and alcohol. I mean, once in a while I’ll drink, but it’s really a rare occasion. I’ve never done drugs and I don’t smoke. I hate it. I like being really lucid. I like being in control.”

In Confessions of a Pretty Lady, Bernhard writes: “I long to become the best version of myself I can be. I look for perfection, the dusted table, the silken skin. I want fantasy to appear and never go away. I want all my papers in order and clutter down to a bare minimum.”

There is something else she wants. It may come as a surprise, considering her show includes a fond rendition, in lilting falsetto, of Me and Mrs. Jones.

“I want to have a baby,” Bernhard says, “and the older I get the more I want to have it. I like the idea of having a kid and raising it and seeing what happens.”

It is not that she hears the biological clock ticking, and it is definitely not that she wants to settle down. She says, flat out, the prerequisite for her sire won’t necessarily be true love. And as much as Bernhard would like to be a mother, adoption is not an option.

“I’d rather have my own child, to tell you the truth,” she says. “Better breeding. Better quality control.”