The following report courtesy of Peter Lauria:

MÖTLEY CRÜE bassist Nikki Sixx recalls celebrating Christmas Day 1986 in a most unusual way: crouched naked under the tree with a needle in one arm watching his “holiday spirit coagulate in a spoon.”

Twenty-one years later, the Sixx is two unlikely things - alive, and a sober inspiration to a legion of fans who grew up thinking that, if you weren’t partying as hard as the Crüe, you weren’t partying at all.

Sixx, 48, was in town last week to hawk his new book, The Heroin Diaries. Roughly 1,000 people descended on Virgin Records in Times Square to get an autographed copy.

“Rather than just talking about a drug problem, this book made me remember what addiction felt like,” says one fan, Joanie, adding that reading about the feeling was almost as bad as going through it.

A lot of people know what addiction feels like: More than 22 million age 12 or older - roughly 10 percent of the U.S. population - needed treatment for alcohol or drug addiction in 2003, according to the Substance Abuse and Mental Health Services Administration. Only a fraction - 1.2 million - got it.

Enter Sixx.

The lanky creative core of Mötley Crüe has become a vocal advocate for recovery. Last month, the wild-haired, tattoo-covered Sixx, born Frank Feranna, was the first rock star to speak on Capitol Hill at the invitation of the Association of Addiction Professionals.

The Heroin Diaries debuted at No. 7 on the New York Times nonfiction best-seller list, having already outsold Mötley Crüe’s collective effort, “The Dirt.” Twenty-five percent of the book’s proceeds are being donated to “Running Wild in the Night,” a fund-raising initiative set up by Sixx for Covenant House.

Sixx is refreshingly modest about his efforts.

“It’s just a year of giving back for me, dude, no strings attached,” Sixx says.

Sixx, who never became tabloid fodder the way bandmates Tommy Lee and Vince Neil did, said he was relieved that as many people were drawing inspiration from the book as were reading it simply for the debauched tales.

“Sometimes you have a vision but the message doesn’t get across,” says Sixx, who, during the course of selling 45 million albums, was simultaneously so strung out that he was literally dead for a few minutes in 1987. “This time I’m feeling that everyone’s getting it.”

Indeed, a blonde woman named Jeri, two years free from heroin addiction, thanked Sixx for writing the book and says she planned to show it to her still-addicted brother, a longtime Crüe fan, in the hopes of doing some good.

And it just might.

“The stigma associated with addiction can put people in the helpless position of feeling like they can’t relate to others,” says Christopher Taylor, an addiction therapist and secretary for AAP New York. “A person of Nikki’s stature being so honest about addiction can inspire someone to live differently.”

Sixx’s new philosophy is that you have to be selfless to be sober, and he could be onto something. At one point during the book signing, right after Sixx put his John Hancock on a bald guy’s head, two girls no more than 20 years old got their turn in front of the rocker.

Sober now, they proceeded to tell a tale of life as abandoned teenagers living on the streets addicted to junk - a past Sixx can relate to.

“That’s exactly what I’m talking about,” he tells The Post. “That’s like money in the spiritual bank.”