Forgive yourself if you are seeing Jennifer Lopez in your sleep. She is everywhere else these days, too.

You can hardly pass a billboard in New York City without seeing her face plastered on advertisements for her new movie, ''Maid In Manhattan.'' Last Friday, she could be seen on ''The Today Show,'' bellowing out three singles from her new album, ''This Is Me . . . Then.'' Entire newsstands seem to be devoted to the sole theme of ''What is Jennifer Doing This Very Minute?'' On the cover of the December issue of GQ magazine, she vamps for the camera, wrapped only in a clinging white cloth.

Ms. Lopez's singing and acting talents have received mixed reviews, but that has not stopped her from becoming a cultural icon. She is one of the biggest female celebrities in entertainment today.

But her popularity has dangers, the main one being overexposure. And Ms. Lopez's attempt to branch out from her hip-hip roots is gathering whispers that she could be spreading herself too thin.

Will Jennifer Lopez last?

If she cannot, it will not be because Sony Music Entertainment, the parent company of her label, Epic Records, which took up her cause four years ago, has not tried.

The model is Madonna, still going strong in her 40's, through the freshness of reinvention. Ms. Lopez, known as J. Lo, is the latest in a string of diva creations by Thomas D. Mottola, chairman and chief executive of Sony Music Entertainment, a unit of the Sony Corporation. Mr. Mottola and Ms. Lopez's manager, Benny Medina, have carefully cultivated and groomed her career, sprinkling her image with a dash of ''ghetto fabulousness'' here and a dash of middle-class respectability there to give her mass appeal.

Few actresses have made the successful transition to singing. Some think Ms. Lopez's best bet for longevity may be to just stay with the acting.

''While she is releasing great danceable music,'' said Stephen Hill, vice president for music and talent at Black Entertainment Television, ''the changes in acting are much less volatile than music.''

Some music critics say Ms. Lopez's soaring popularity on the pop charts, her glamorous roles in mainstream movies and her highly publicized personal life, highlighted by her engagement to the actor Ben Affleck, have jeopardized her following within her core fan base: the black and Hispanic hip-hop community.

Her handlers have sensed the danger, Mr. Mottola said. They came up with an idea for a new single, ''Jenny From the Block,'' that essentially tells her fans that she is still a home girl even though she is ''bling-blinging'' -- wearing expensive diamonds and furs.

The strategy seems to have worked. ''This Is Me . . . Then,'' which features the new single, sold 314,132 copies last week, her biggest album debut ever, according to Nielsen Soundscan, which tracks record sales. Ms. Lopez sold 272,252 copies when her last album, ''J. Lo,'' went on sale two years ago, according to Soundscan.

It is this kind of loyalty that executives at Revolution Studios are hoping for when ''Maid In Manhattan'' opens on Friday. The film has a ''Working Girl'' story line. Ms. Lopez plays a maid at a swanky hotel who is mistaken for a hotel guest by a patrician Senate candidate (Ralph Fiennes), and the two fall in love. The aim is to create a crossover bull's-eye. Sony Pictures Entertainment owns a 7.5 percent stake in Revolution Studios.

Mr. Mottola, who was a mentor to Gloria Estefan, Mariah Carey, Celine Dion and most recently Shakira, has helped Ms. Lopez's manager, Mr. Medina, build her career. The three confer on all matters, from which tracks to put on an album to movie scripts and ways to tweak her image, Mr. Mottola said.

''The relationship can be as creative and productive as it is adversarial,'' Mr. Medina said. ''It is adversarial for all the right reasons. When we all agree, it's a beautiful day.''

Ms. Lopez's first break came when she worked as a ''fly girl,'' dancing on the Fox comedy-skit series ''In Living Color'' in 1990. After acting in small roles in several television series, she got her first part in a major movie in 1995 with ''Money Train,'' starring Wesley Snipes and Woody Harrelson. She won another role in the feature ''Anaconda'' and got top billing (and $1 million). Then, in 1997, she gained an even wider Hispanic following for her lead role in ''Selena,'' the movie biography of the Mexican-American singing idol.

A performance in 1998 in ''Out of Sight'' helped her gain greater mainstream acceptance. In the film, which was directed by Steven Soderbergh, she plays a tough and sexy deputy federal marshal who is locked in a trunk with an escaped convict, played by George Clooney.

She decided she wanted to sing, and Mr. Mottola became involved. He used her momentum to build a strong hip-hop fan base for her music among young blacks and Hispanics, especially in the Bronx.

In 1998, Mr. Mottola had street teams generate a buzz about her coming album, ''On the Six,'' in schools, restaurants and bars and on Spanish language radio stations. He reached out to P. Diddy, then known as Puff Daddy, to produce a track on the album, which was released in 1999. Further, he paired her with Cory Rooney, a producer with strong roots in rhythm-and-blues.

''Back then it all seemed so fast,'' Ms. Lopez said. ''Not a week after I signed my contract with Epic Records in 1998, they started doing all this big stuff. I got all of these calls: 'Tommy wants you to come to his office. You are going to meet with your producers.' I got to meet Baby Face and Ric Wake, all the people who were working Mariah Carey.

''Cory Rooney, who is my producer to this day, was like, 'Oh, Tommy has a plan,' '' Ms. Lopez continued. ''People were saying, 'Isn't she an actress?' One producer said that he wanted to hear me sing. Tommy was like: 'You don't have to hear her sing. She does pop and a little bit of Latin and R & B.' He was very protective.''

Ms. Lopez and P. Diddy became an item -- a linkage with serious crossover implications. Evolving into a paparazzi favorite, she earned street credibility when she stuck by her man during a trial over a nightclub shooting in 1999. Some in the music industry said she risked losing her broader audience, but that danger ended when she left P. Diddy in 2001, the same year he was acquitted of all charges related to the shooting.

At first, the buzz surrounding Ms. Lopez and P. Diddy ''was 1,000 percent cool and put her right into the streets,'' Mr. Mottola said of Ms. Lopez and P. Diddy.

Even after she ended her relationship with P. Diddy, her popularity took on a life of its own, and Sony and Ms. Lopez began force-feeding her image to the public. They also timed the release of films and CD's to gain maximum publicity benefit. The strategy paid off in January 2001, when she had the No. 1 movie, ''The Wedding Planner,'' and the No. 1 album, ''J. Lo.''

Ms. Lopez has capitalized on her popularity to promote her clothing line, J. Lo, and her fragrance, Glow.

The clothing line, which got off to a rocky start last year, is performing exceptionally well, said Ronnie Taffet, a spokeswoman for Macy's at Herald Square. In August, her fragrance, Glow, was the store's second-largest women's launch in seven years.

''She has developed a much broader following, which has helped her clothing line,'' Ms. Taffet said.

So continue to expect Ms. Lopez everywhere. Sony is negotiating a deal to run a Jennifer Lopez prime time television special on Feb. 12, Mr. Mottola said. In addition, a new video game, ''Jen Saves Ben,'' features Ms. Lopez rescuing Mr. Affleck from kidnappers.

Gone are the days when artists could just record a CD, pose for a magazine or billboard promotion and be finished with a record. Internet piracy, greater media choices and declining CD sales have forced music companies to work harder to persuade consumers to buy music. Artists must go on exhaustive promotion campaigns, showing up on morning news shows and prime-time specials. They must be more open to fans than they were a decade ago. As a result, artists are more willing to risk overexposure.

''Today, artists are coming at you from all directions, but they want that,'' said Sir Howard Stringer, the chief executive of the Sony Corporation of America. ''It's no longer just do your music, sell your CD and goodbye. Piracy and problems in music companies have forced everyone to think outside of the box.''