Courtesy of Colleen Nick

Morgan Nick vanished at a Little League game when she was 6 years old in 1995. Nearly two decades later, her mother hasn't given up hope that she'll come home, just like the three women discovered Monday afternoon in Cleveland.

Elizabeth Smart. Jaycee Dugard. Shawn Hornbeck. Many parents of missing children repeat these names like a mantra -- each one is evidence that their long-lost child is not a lost cause.

Now Amanda Berry, Gina DeJesus and Michele Knight can be added to that list of found children. The discovery of the three Ohio women on Monday is exactly the kind of hope that keeps parents of missing children going, long after their search has stopped making sense to us outsiders.

“Whether that hope is a realistic hope varies enormously from one situation to the next,” says Gregory Greif, a professor of social work at the University of Maryland who has worked with families of long-term missing children. “With non-family abductions, when children are missing for more than a decade, it’s extremely rare for a child to be found.”

Nearly 800,000 children vanish each year -- that’s an average of 2,185 every day, according to the latest statistics from the U.S. Department of Justice. About 99 percent of children taken by strangers return home alive, most of them within 24 hours. After 24 hours, the chance of recovering the lost child shrinks.

“Basically, when you’re talking about kids who’ve been abducted by strangers, only [a small percentage] of those actually make it back home,” says Colleen Nick, whose 6-year-old daughter Morgan disappeared on June 9, 1995. But even that small number means there is a chance, she adds. 

"My reaction to this amazing recovery is joy," Nick says of the women found in Cleveland. "My daughter is missing long-term and I fight for her every day. We know that there are kids out there waiting to be recovered, and it really takes an everyday hero. We know that kids come home."

Slideshow: Missing women found alive in Cleveland

Tony Dejak / AP

A daring escape and a dramatic 911 call led to the rescue of three women who allegedly had been held captive for years inside a home in Cleveland, Ohio.

Launch slideshow

On an early summer day 18 years ago, Morgan and her mother were watching a Little League game in Alma, Ark., 30 miles away from their home in Ozark, Ark., when the little girl asked to go off with a couple friends to catch fireflies. “She stopped to take sand out of her shoe, and the other two children walked off,” Nick says. That was the last time anyone saw Morgan.

In the weeks that followed, Nick and her husband halted their lives. The couple’s younger two children, then ages 2-and-a-half and 22 months, stayed with their grandmother, while the parents moved into the Alma fire station, where they lived for six weeks.

“We were completely consumed with the search,” Nick says. After those six weeks, they left Alma and returned to Ozark. Life would never be normal again, but as she explains it, “you have to learn to survive. If you have other children, they have to go to school, you have to go back to work.”

That can be one of the most wrenching decisions for a parent of a long-term missing child: When the boy or girl initially vanishes, the parents stop their lives and focus every possible moment on bringing the child home. But it’s impossible to keep that kind of intensity up forever.

“The terrible struggle for parents of missing children is they have to resolve how much to search,” says Greif. “If a child is missing, that parent is going to search 24 hours a day. And you do that for a week, and you do that for a month, but at what point do you have to go back to your job and your partner and family and friends? And no one can answer that for anybody.”

'Open-ended grief'
Families of lost children deal with what psychologists call ambiguous grief, a term coined by University of Minnesota social scientist Pauline Boss to describe the loss of a loved one without the certainty of death. The term can apply to families of missing children, but also families of soldiers missing in action, or even those whose loved ones have developed Alzheimer’s.

Without the ritual of a funeral or memorial service, which many families choose not to hold if they believe their child may still be alive, some decide to mark the birthdate or the day the child disappeared by gathering with friends and family.

Amanda Berry’s mother, Louwana Miller, held a vigil on her daughter’s birthday in 2005, two years after the girl’s disappearance; friends, family and supporters completed the walk home that Amanda did not on the day she disappeared, and when they reached their home, they sang happy birthday to Amanda, the Cleveland Plain Dealer reported that year.  

Courtesy Colleen Nick

This age-adjusted image reflects what Morgan Nick might look like today.

Miller died at age 43 of heart failure after searching for her daughter for three years.  

Nick and her family remember Morgan each year on her “disappearance day” by gathering together and releasing pink balloons into the air. “We always have a big gathering on her missing day,” Nick says. “But I really hold her birthday for myself and I usually spend it very quietly.”

Janis McCall, whose daughter Stacy vanished more than 20 years ago when she was 18 years old, gathers loved ones together on the anniversary of Stacy’s disappearance -- June 7, 1992. “Anything to keep her in people’s minds,” McCall says. Last year, they held a candlelight vigil at 6 a.m., around the time Stacy is believed to have vanished from a friend’s Springfield, Mo., home, where she was spending the night after her high school graduation. Adding to the mystery, Stacy’s friend and the friend’s mother were also never seen again after that night. “And that’s all we know,” McCall says.

McCall spoke to NBCNews.com on the phone from Jacksonville, Fla., where she was attending the 2013 Amber Alert Symposium with law enforcement officials and other families of missing children. Even 20 years later, she still posts fliers with Stacy’s photo, but only “occasionally” now. 

“I think of it as open-ended grief,” Nick says. “It’s always there. There are no answers for it. You do learn to function again. But it just takes really very small things to just rip that wide open again, because it’s always there. A part of my heart is walking around outside of my body.”

Incredible stories of discovery, like that of the missing Ohio women, can shake whatever fragile sense of resolution a family or parent has reached over the years. But Greif and other experts resist the term “false hope,” and don’t believe that the encouragement this story may bring to families of lost children is always damaging.

“You and I cannot sit here and say that having hope come from this is necessarily a bad thing,” Greif says. “I don’t know. I think maybe for some people it could be injurious, and for some people, it could allow them to have a moment of joy.”

Some well-meaning friends have encouraged Nick to "seek closure," to move on with her life. “They do say things like, 'Maybe you should do a little more realistic, wouldn’t you feel better if you could accept that Morgan is dead and you’ll see her again in heaven,'” she says. But even today, nearly two decades after her daughter's disappearance, Nick posts fliers and maintains a website with pictures of what Morgan might look like today. She also started the Morgan Nick Foundation, to help families of missing children with things like childcare in the immediate aftermath of the disappearance.

As her two younger children grew up, Nick focused on finding Morgan during the school day. (She and her husband are now separated.) But when the children were home, she says she tried hard to be present for the two kids who were still there. 

“You try to eventually find some joy in your family,” she says. "You have to learn to laugh again, because if you don’t, this will destroy you.”

Related stories:

• Women's rescue a triumph and relief for searchers who 'never gave up'
• 'Never get over what happened': Captives face psychic toll
• Timeline of Ohio kidnapping: Three women's shared nightmare

I’m stressed, you’re stressed, your partner is stressed, even our pets are stressed. But according a new survey from the American Psychological Association, the most stressed generation of adults in the nation is also the youngest.

So-called “Millennials,” defined here as American adults ages 18 to 34, reported higher stress levels than their parents’ and grandparents’ generations, and more Millennials said that their stress level had increased in the last year. And 52 percent of this age group even said stress had kept them up at night.

These new figures are from the APA’s annual report, Stress in America, which surveyed 2,020 American adults in a questionnaire conducted online by Harris Interactive in August 2012. The APA has commissioned the survey every year since 2007.

Generation Xers’ stress level was tied with Millennials, both reporting an average level of 5.4 on a 10-point scale, but slightly fewer Gen Xers, those aged 34 to 47, said their stress increased in the past year or was causing them to lose sleep.

It doesn’t take much imagination to figure out what young people might be stressing over: For one, the U.S. unemployment rate continues to creep higher, last week edging up to 7.9 percent. Some recent figures from the non-partisan group Generation Opportunity suggest the unemployment rate is even higher among 18- to 29-year-olds, at 11.5 percent, and only half of this age group believe they’ll be getting Social Security.

“Most of these young people have come out of college or graduate school with horrendous student debt into a job market where there are not very many jobs,” Katherine Nordal , executive director for professional practice of the APA, told “NBC Nightly News with Brian Williams.” “This has put their life plans probably on hiatus; they may be postponing marriage, postponing having a family.”

The APA survey found that 76 percent of Millennials surveyed by the APA say that work is a somewhat or significant stressor, compared to 65 percent of Gen Xers and 62 percent of Boomers. That’s a number that has been ticking upwards -- in the APA’s 2009 survey, for example, less than half of Millennials reported work as a somewhat or significant stressor.

And, as it turns out, young adults are not great at handling all this self-reported stress they’re under: Forty-four percent of both Millenials and Gen Xers say they’d experienced irritability or anger due to stress, compared to 36 percent of Boomers and 15 percent of what the APA deemed “Matures,” or Americans older than 67.

“Stress is a huge factor when we look at medical problems such as obesity, hypertension, diabetes, cardiac disease,” says NBC’s chief medical editor, Dr. Nancy Snyderman. That’s more bad news for younger Americans, who say they more likely than older generations to try to manage their stress by eating junk, drinking alcohol and smoking.

It's tempting to raise an eyebrow at the findings because the stress is self-reported: How are we sure that young people are really under as much stress as they say? To a certain extent, that doesn't really matter. If you perceive yourself to be under an incredible amount of stress, then that stress is real to you, says Gail Saltz, an New York City psychiatrist and frequent TODAY contributor. 

"I think that does have something to do about the acquisition of coping skills," Saltz says. "As you manage to get past things, your ability to look back as something else comes along and say, 'Well, I got through that' -- that goes a long way." 

We do seem to get better at managing stress as we age, according to the APA’s self-reported figures. While 29 percent of Millennials, 35 percent of Gen Xers and 38 percent of Boomers (adults aged 48 to 66) said they are doing an excellent or very good job at managing stress, half of those older than 67 thought they were doing a bang-up job of keeping their stress manageable. 

"There really is something to 'what doesn't kill you makes you stronger,'" Saltz says.