IF you’ve gone back to unhealthy habits like smoking and drinking since the World Trade Center attack, apparently you’re not alone.

“I started smoking and now I’m up to a pack every three days,” says Kathleen Dunleavy, who works in Manhattan and quit smoking five years ago. She also has turned to junk food (in fact, she was eating a slice of meatball pizza at her desk when The Post called) and stopped going to the gym.

“It comes from being afraid, from being afraid something else will happen. I feel like we’re going to die. I feel like I may as well enjoy myself now.”

Still she doesn’t feel better. “I’ve got a sore throat and I’m tired all the time,” says Dunleavy, who’s trying cut back this week.

One Manhattan psychologist said many New Yorkers share Dunleavy’s problem right now.

“Cigarettes are a stress reliever,” explains Dr. Iris McGuire. “When people are stressed out they look for comfort all over.”

Patty, who lives in Queens, says she’s been on an “all-out binge” – using alcohol, food and cigarettes to deal with the stress. She also hooked up with an old boyfriend.

“It’s a little bit of everything – devil may care, throw caution to the wind, we’ll be blown up tomorrow. It’s also self-destructive. When I get frightened. I don’t act out, I turn inward.”

When asked about cigarettes, Patty replied, “Are you kidding? I don’t bother with plain old air anymore. I smoke in my sleep,’ she says. “Cigarettes are a quick anti-depressant.”

McGuire’s advice? “Try to relieve stress some other way – through exercise like walking, jogging, swimming, or any kind of physical act.”