Updated

While an over-inflated ego never hurts if you're trying to get noticed in Hollywood, some stars need attention to such a degree, some wonder if something more serious is going on beneath their often photographed surfaces.

Exhibit One: Kim Kardashian.

Under the guise of “Flashback Friday,” the reality star felt the need to post five-year-old pictures of herself in a barely-there red swimsuit being primed and pampered for her 2007 Playboy shoot. Twelve hours before that, on Thursday, she posted pictures of herself indulging in a “night swim” for a shoot, donning black bikini bottoms and a sexy top, with her legs spread slightly apart as the waves rolled in, and another of her leering directly into the camera while frolicking in the water.

A few hours earlier, Kardashian posted a picture of herself with younger sister Kylie during a skeet shooting session while vacationing in the Dominican Republic. Four hours before that, the reality star tweeted yet another picture of her bare-skinned self driving a car, and later wrote:  “Wait why does the pic of my driving look like I'm naked!!??!! I'm wearing a strapless dress!!! LOL.”

HOT SHOTS: Kim Kardashian.

More On This...

Then, instead of “Flashback Friday,” Kardashian used the excuse of “Throwback Thursday” as a reason to post a photo of herself in a black bikini and lots of bling alongside her sisters, also in their bikinis.

We're not done.

On Wednesday, Kardashian posted another round of bikini pictures of herself in Hawaii, and on the same day covered up a little more with a blog post about “cozying up for Fall” and a professional photograph of the Kardashian sisters. Tuesday welcomed a bevy of pics including a charming photo of herself and her sisters giving the finger while out dining to describe “how (she was) feeling right about now,” “flashback” birthday photos of herself in a tight sparkly dress surrounded by friends and family, and more family snaps of Kim pouting her lips.

On Monday she posted a photo in an uber-tight purple dress with male hands around her waist and a come-hither expression, as well as a link to a boat for sale on eBay which featured a dramatic photo of her in a cleavage-baring black swimsuit running her fingers through her hair. That was all after posting a 2008 shoot of herself in an Audrey Hepburn “Funny Face” inspired photo shoot, and another promo pic alongside her sisters.

There is so much more, but you get the picture(s). And while Kardashian's self-promotion looks to be unbeatable, there is one other celeb who's making a serious run for that Most Conceited Star statue.

Exhibit Two: Miley Cyrus.

On Friday, Miley Cyrus posted a self-taken snap of herself showing off “CUHHH-RAZY pants” and her new platinum pixie ‘do – in a see-through top, naturally. This capped off a week of continual photo postings of her and her hair from a multitude of angles and different makeup looks, another self-photo showing off her toned midriff and another in short shorts. This was all interspersed with tweets such as “someone just told me I am prettier than Miley Cyrus,” and others about being “happy” and “comfortable in my skin,” her joy at being the Marie Claire profile pic, a re-tweet about her being “one of the most fashion-forward PYTs.” Again, we could be here all day…

HOT SHOTS: Miley Cyrus.

Some experts we talked to said the type of behavior demonstrated by Kardashian and Cyrus runs deeper than super self-confidence or look-at-me mania.

“Kim and Miley’s actions are not about ego or common narcissistic behavior – they are acting out in response to extreme stress or they are verging on Narcissistic Personality Disorder. NPD is recognized by promiscuous behavior, an aggressive response to criticism, and the extreme need to be the center of attention at all times,” said human behavior expert, Patrick Wanis M.D. “It appears now that their actions are out of control because the need to constantly expose themselves to the world is now controlling them.”

Los Angeles-based therapist Dr. Nancy Irwin also noted that the sexy photo streaming could potentially have a very detrimental effect on both girls’ fan bases.

“It appears that both these young ladies are addicted to mass attention, yet it could send a negative message to young girls that your sexuality is a tool for attention,” she explained. “Other stars who are in a career slump or lag may use substances or other unhealthy coping tools during tough times. In Hollywood, sex is used a lot – especially by women who have gotten a great deal of attention with their looks.”

But P.R. guru Ronn Torossian said their behavior is relatively harmless and nothing out of the ordinary.

"Kim Kardashian is a beautiful young woman who is known for her looks more than anything else. What is surprising about a woman famous for her looks tweeting sexy bikini shots? Kim has made millions because of her brand and her looks," he said. "And Miley is now 19 years old, and clearly has strayed very far from her role as Hannah Montana. No one following either Kim or Miley should be surprised at their antics on Twitter. If you expected history or philosophy, you shouldn't be following either of them."

While the two are still mainstays on magazine covers, quite a few fans say they're getting fed up with the never-ending photo bombardment.

“Sick of seeing Miley Cyrus pix she takes & tweets of herself all day. ego maniac much?” tweeted one, while another wrote: "If I don't see a photo of Kim Kardashian in a bikini from her 'personal photo collection' ever again, I think I'll live."

Reps for Kardashian and Cyrus did not respond to a request for comment.

Danielle Jones-Wesley contributed to this report.