Viewing sexually explicit programs or content on websites may not truly influence whether a young adult will have risky sex or lots of partners, a new study from the Netherlands shows.

Watching porn only affects sexual behavior a little bit. It can prompt someone to be more likely to have a one-night stand or have sex for money, according to the report released Thursday in the Journal of Sexual Medicine. But other influences such as personality type, educational and family background, and poverty hold more sway than viewing sexually explicit material. The study, led by Gert Martin Hald of the Department of Public Health at the University of Copenhagen, surveyed 4,600 young people between the ages of 15 and 25 living in the Netherlands during 2008-2009.

They found that 88 percent of the young men and 45 percent of young women had viewed sexually explicit media over the past 12 months. All kinds of porn, including bondage, soft core, and violent images were included, but the influence of that porn on behavior, though scientifically significant, was small. 

The sexual behaviors were classified into three broad areas: adventurous sex such as threesomes or sex with someone met online; partner experience, such as one-night stands; and transactional sex, involving payment.  

More porn viewing was associated with a greater likelihood that young adults would say “yes” to one or more of these behaviors.  

But that’s not the end of the story. Importantly, Hald and his team also asked questions gauging traits like sexual sensation-seeking -- how driven a person is to seek new experiences -- as well as gender, age, education, religious belief, relationship status and ethnicity, self-esteem and others.

Few studies have tried to incorporate these other factors, but, Hald told NBCNews.com “associations between porn and sexual behavior or attitudes really always should be studied in conjunction with other relevant factors, such as personality.”

When all those variables were taken into account, it turned out that all those behaviors were also highly associated with the personality type of sexual sensation-seeking.

For example, Hald explained, “only 2-3 percent of our sample engaged in transactional behaviors, and the proportion of these behaviors explained by porn viewing was only 1 percent for men and 2 percent for women.” Other factors, he said, such as poverty and culture, were more important.

That was true across the board. The frequency of looking at porn explained only about .3 to 4 percent of behavior.

“This suggests that frequency of [porn] consumption is just one factor among many that may influence the sexual behaviors of young people,” the study concluded.

It’s not that porn has no effect. But many other factors are in play. For example, Hald said his Netherlands sample may differ somewhat from an American one given the Netherlands somewhat more liberal sexual cultures where, for example, prostitution is legal."I think that the social and sexual context of viewing pornography impacts the association between pornography and the sexual behavioral outcomes studied," Hald said.

Chauntelle Tibbals, a sociologist at the University of Southern California who studies the adult entertainment industry, agreed.

She pointed out that watching porn is illegal for those under 18 and that younger people who have not had much sexual experience, nor solid much sexual education, may turn to porn for sex clues. “If you did not already know about this in real life, or have sex education, or experience it with a peer, and you see it in porn, you may think, ‘Oh, I want to do that.’”

But she agreed with Hald that watching porn was only one small influence among other, larger influences.

It comes down to what’s driving the train. Hald suggested that things like age at which one first has sex, oral sex behaviors, and porn consumption are really the passengers on a train driven by personality, family, education and economic status. 

“I would say that it may likely be that personal dispositions such as sensation seeking may be what is essential,” he said. 

It’s not that watching porn has no effect. It’s that porn doesn’t exist in a vacuum. “Pornography adds to increases in the sexual behaviors and attitudes we studied, but this contribution is modest.”

Brian Alexander (www.BrianRAlexander.com) is co-author, with Larry Young Ph.D., of "The Chemistry Between Us: Love, Sex and the Science of Attraction," (www.TheChemistryBetweenUs.com), now on sale.

Mark Lennihan / AP

Harry Patel, an employee of Blondie's Deli and Grocery, talks on the phone while waiting for customers in New York on Monday. A new anti-smoking proposal would make New York the first city in the nation to keep tobacco products out of sight in retail stores. Mayor Michael Bloomberg says the goal is to reduce the youth smoking rate.

New York City Mayor Michael Bloomberg raised eyebrows Monday, proposing a new law – the first of its kind in the nation – that would require cigarettes and other tobacco products be hidden from view of shoppers.

“We know that out of sight doesn’t always mean out of mind,” Bloomberg said during a news conference at Queens Hospital Center. “But in many cases it can and we think this measure will help reduce impulse purchases and if it does, it will literally save lives.”

Experts say there is evidence that the mere sight of a pack of cigarettes really can make smokers want to buy them.

“Nicotine is the most addictive drug there is and cigarettes are both biologically and psychologically addictive,” says Dr. Gail Saltz, a NYC psychiatrist, author and regular TODAY contributor. “Seeing cigarettes is a trigger. ‘There it is.’ It very well may make you want it more.”

Numerous studies back this up. A 2008 study published in the journal Addiction surveyed nearly 3,000 adults (including smokers, ex-smokers and those currently trying to quit) and found more than 25 percent of smokers bought cigarettes after seeing a cash register display -- even though they weren’t shopping for smokes. And one in five smokers trying to quit said they avoided the stores where they usually bought cigarettes because they knew if they went in, they’d buy them.

The allure is so strong even 31 percent of smokers readily admitted that removing cigarettes from store displays would make it much easier to quit.

“Point of purchase cigarette displays act as cues to smoke, even among those not explicitly intending to buy cigarettes and those trying to avoid smoking,” wrote psychologist and lead author Melanie Wakefield, director of the Centre for Behavioural Research in Cancer in Victoria, Australia. “Effective POP marketing restrictions should encompass cigarette displays.”

Other studies have shown store cigarette promotions are strongly correlated with rates of youths taking up smoking as well as increased tobacco sales in the stores. A 2009 study in the journal Tobacco Control found that one of five shoppers who bought smokes at retail outlets with cigarettes on display at the check-out counter made an impulse buy.

“Visual triggers are a huge part of addiction,” says Joe Guppy, Seattle psychotherapist and addiction specialist. “That’s why when people are in recovery, they try to avoid visual triggers. I once had a client mention a magazine ad he saw once when he was trying to quit smoking. It showed a man taking that first drag off a cigarette, looking right into the camera. It probably took thousands of shots to capture that exact moment. But when it hit his brain, it made him go, ‘Oh, I want that so bad.’”

Adds Danny McGoldrick, vice president of research for Campaign for Tobacco-Free Kids, “Impulse buying can occur when you’re exposed to a number of different product displays but particularly if you have nicotine addiction.”

Guppy hails Bloomberg’s proposal, adding that “out of sight, out of mind” can be helpful with all kinds of addictions – from internet porn to sweets.

“I have a thing with chocolate,” he says. “If I want to moderate my intake of brownies, I’ll put them on top of the refrigerator instead of on the counter. That way, I’m not constantly triggered.”

Saltz warns that when it comes to something as addictive as nicotine, though, out of sight, out of mind may not always work.

“It’s not that simple because nicotine is addictive you’re going to seek it anyway if you’re already addicted,” she says. “But for people who may be trying to stay away and may not particularly be shopping for them, it would be better if it’s not in their face.”

Related:

• After big soda ban, NYC's Mayor Bloomberg wants to hide cigarettes
• Smoking costs you a decade of life
• A staggering teen smoking epidemic

You surely know by now that the Powerball jackpot is set to hit at least $550 million tonight. You should also know that your odds of winning the grand prize are somewhere around 1 in 176 million (at least, we really hope you know that). So here's a bit of comfort for you tonight as you stare dejectedly at your losing ticket: Most lottery winners don't end up any happier than the rest of us. 

Yeah, yeah, you can probably name 550 million reasons why winning the jackpot tonight will make you happy. But here's the truth: A handful of psychology studies over the years have evaluated the happiness of lottery winners over time, and found that after the initial glee of getting one of those big giant checks has faded away, most winners actually end up no happier than they were before hitting the jackpot.

Arguably the most famous paper on this subject was published the late 1970s, and it's a doozy: Psychologists interviewed winners of the Illinois State Lottery and compared them with non-winners -- and, just for good measure, people who had suffered some terrible accident that left them paraplegic or quadriplegic. (You can find the abstract here, but you'll have to pay to read the full report.) Each group answered a series of questions designed to measure their level of happiness.

Joe Raedle / Getty Images

Stefanie Graef holds what she hopes is the winning Powerball ticket she just bought at Circle News Stand on Tuesday in Hollywood, Fla. If she's lucky, she won't win.

What they found was counterintuitive, to say the least: In terms of overall happiness, the lottery winners were not significantly happier than the non-lottery winners. (The accident victims were less happy, but not by much.) But when it came to rating everyday happiness, the lottery winners took "significantly less pleasure" in the simple things like chatting with a friend, reading a magazine or receiving a compliment. 

"Humans tend to have a relatively set point of mood," explains Gail Saltz, a New York City psychiatrist and frequent TODAY contributor. Most people tend to bounce back to that set point after a major life event, whether it's something negative or positive. But for some lottery winners, psychologists believe hitting an especially huge jackpot may alter that happiness baseline, making it harder to see the joy in everyday things. 

More recently than the '70s research, a 2008 University of California, Santa Barbara, paper measured people's happiness six months after winning a relatively modest lottery prize -- a lump sum equivalent to about eight months' worth of income. "We found that this had zero detectable effect on happiness at that time," says Peter Kuhn, one of the study authors and a professor of economics at the university. 

Andrew Jackson "Jack'' Whittaker Jr., his wife Jewell, right, and their granddaughter Brandi Bragg, left, pose for a photograph after being interviewed by TODAY in this December 2002. In his darkest moments, Whittaker has said he sometimes wondered if winning the nearly $315 million Powerball game was really worth it.

You've heard the stories of lottery winners whose post-jackpot lives turned sour. There's Jack Whittaker, the West Virginia man who in 2002 won the nearly $315 million Powerball jackpot. Initially, he generously gave millions to charities, including $14 million to start his own Jack Whittaker Foundation. But later, the dream turned to nightmare: A briefcase with $545,000 in cash and cashier's checks was stolen from his car while it was parked outside of a Cross Lanes, W. Va., strip club. His office and home were broken into, he was arrested twice for drunken-driving -- and the list goes on. 

Or there's Alex Toth, a Florida man who in 1990 won $13 million to be doled out in 20-year-payments of $666,666. (Seriously.) At his death in 2008, the Tampa Bay Times reported on the sad direction his life had taken: Years of living it up led to a split from his wife and charges of fradulent tax returns, among other serious woes.

What gives? Behavior experts have a couple theories. One is simply that we humans just tend to get used to stuff -- the good and the bad. The psychological concept is called "happiness adaptation," and Michael Norton, associate professor at Harvard Business School, co-authored a 2007 paper that sought to uncover why hitting major life goals -- including the dreamlike goal of winning the lottery and the more down-to-earth goal of getting married -- don't end up making us as happy as we expect them to. 

"The idea of adaptation seems like a negative thing --  it's a shame that we have to get used to the good things in our life, from lottery winnings to ice cream. But adaptation also helps us when bad things happen to us, making the impact of losing our job or getting divorced less painful over time," explains Norton, who is also the coauthor of the forthcoming book, "Happy Money: The Science of Smarter Spending." 

He continues, "Big positive and negative events can have a lasting impact on our happiness, but this impact tends to decrease over time. In some sense, because people have so many facets of their life - from their job to their friends to their family to their hobbies - the impact of a change in any one of those facets is less extreme than we think, because many of the other things in our lives stay the same. (We win the lottery but we are still stuck with our same siblings, for example.) As a result of this, people tend to adapt to life events and end up closer to where they were than they think they'd be."

This is partially because we are terrible at predicting how happy more money is going to make us. The truth is, money can make you happy -- but only up to a point. "Research shows that the impact of additional income on happiness begins to level off around $75,000 of income - but people keep trying to make more and more money in the mistaken belief that their happiness will continue to increase," Norton says. "As a result of this mistaken belief, people think that big windfalls will change their happiness dramatically - and may end up with less happiness than they expected."

On the other end of the spectrum, landing a windfall that lifts you out of a financial pit really can provide significant, lasting happiness. In 2006, Sandra Hayes, then a 46-year-old social worker making $25,000 a year, and 12 of her coworkers won the $224 million Powerball jackpot. After taxes and splitting the money with her coworkers, Hayes had won $10 million. She bought her dream car (a brand-new Lexus) and her dream home (a half-million dollar house in St. Louis). But first, she paid off her current home and then gave that house to her daughter and grandchildren, who'd been living in a rough neighborhood. She quit her job and now spends her days writing -- she's already published one book and is working on a second one. 

"Yes, my life is different, and it feels good," says Hayes. "This summer I had a $900 water bill. Six years ago, well, if I had a substantially huge bill, I would’ve had to make payment arrangements. That’s one of the things I like, that I’m able to pay my bills in full and not scuffle."

The first secret, as Hayes tells it, to winning the lottery without losing your mind is to immediately meet with a financial planner you trust and make a plan that works for you. The second is a little simpler. She says, "Just because you win the lottery, it does not change you as a person."

Related: 

Hey, Powerball winner: Here's your holiday shopping list

Advice for the Powerball winner: Pay taxes

11 crazy things more likely to happen than winning the Powerball jackpot

Follow NBCNews.com health writer Melissa Dahl on Twitter: @melissadahl. 

Chris Graythen / Getty Images

LAPLACE, LA - AUGUST 29: Rescue workers transport residents trapped by rising water from Hurricane Isaac in the River Forest subdivision on August 29, 2012 in LaPlace, Louisiana. The large Level 1 hurricane slowly moved across southeast Louisiana, dumping huge amounts of rain and knocking out power to Louisianans in scattered parts of the state. (Photo by Chris Graythen/Getty Images)

It’s the question so many of us have while watching news coverage of a hurricane or tropical storm like Isaac: Who are these people who don’t leave home even as an angry storm is advancing – and what are they thinking?!

The short answer: For some, the up-and-leaving idea isn’t as easy as it sounds to those of us watching from a safe and dry distance. Actually, a 2009 article published in the journal Psychological Science sought to examine the reasons some people won’t evacuate, despite the urging or even mandates of city and state officials, by asking a group who would know: Hurricane Katrina survivors who weathered the storm at home.

“It seems like asking ‘Why didn't people leave?’ presumes that that's the best option for everyone to make,” says Hilary Bergsieker, who worked with Nicole Stephens, now of Northwestern University, on the study. The fact is, many people lack the resources to escape. Having no money, no mode of transportation and no friends or family in safe places means no choice but to weather the storm. 

In the case of Katrina, those who evacuated before the storm hit were mostly white, mostly middle class; on the other hand, those who stayed were mostly black, mostly working class. The “leavers,” as the Psychological Science paper terms those who fled before the storm, had privileges that they probably took for granted: more education, more money, reliable access to transportation, social networks that extended farther away from the hurricane-hit area, and more access to news reports to warn them of the storm’s severity.

"Middle- and upper-class Americans are more geographically mobile and have more experience traveling nationally and internationally. I think that the familiarity with moving or traveling would contribute to the ability to make a plan for how to evacuate,” says Stephens, who is an assistant professor at the Kellogg School of Management at Northwestern. "On the other hand, if you have spent most of your life in the same community, then you would likely feel more attachment to your home and feel less comfortable as well as less equipped to quickly uproot yourself in response to evacuation orders." 

Even if a person does have the resources at hand to make an escape, it might be unthinkable to leave behind a tightknit community like those you’d find in many parts of coastal Louisiana and Mississippi.

Slideshow: Isaac moves inland

/

A downgraded Isaac floods coastal communities and forces new evacuations, but levees still hold.

Launch slideshow

“There's sort of the physical resources factor, but there's also the psychological factors. That's your world; that's all you know,” says Bergsieker, who is now an assistant professor of psychology at the University of Waterloo in Ontario, Canada. And, as the thinking goes, if your neighbor tells you he’s staying, then you might stay, too – after all, if something happened to him, who would be there to take care of him if you leave? Some of the 79 Katrina survivors interviewed in the 2009 study did have the resources to go, but they didn’t have the heart to leave.

Ariella Cohen moved to New Orleans in 2007, so she wasn’t there when Katrina hit. But in 2008, when Hurricane Gustav started moving toward her city, she decided to stick it out, despite the city's mandatory evacuation order.

“I had friends who had stayed through Katrina, and I had heard all their stories about it, and so I think I also inherited all their jadedness, too,” says Cohen, who wrote about her Gustav close encounter for the website Next American City. “You know, just kind of that New Orleanian attitude of, ‘Whatever! We’re going to stay here. Do you want another beer?’” On a more serious note, her rationale for staying was: 'I’m young, I’m able-bodied and relatively fit. What if someone older and weaker needs me?' “I was, like, 27 at the time, so I was young and strong, and I would be able to help people if the time came,” says Choen, now 31, who lives in Philadelphia, where she works as an editor for the same site that published her 2008 essay.

Mistrust of outsiders – as in, people who aren’t from your community who are claiming to know more than you do about your own home by telling you to leave it – can play a part, too. “This is where you've always been your whole life, and suddenly people on the radio are telling you you have to leave? That may seem like a much more dangerous choice than to stay with people from your church, or people from your block,” Bergsieker says.

Besides, those who live in a hurricane-prone area hear these warnings all the time. It can be easy to stay in denial about an impending storm’s ferocity when the local news station has cried “hurricane” so many times before. (Sometimes that tack pans out: In Cohen’s lucky case, Gustav bypassed New Orleans.)

Read this far and still think anyone who’d ignore a hurricane evacuation mandate must be just plain crazy? That sounds about right. A second piece of the study asked both Katrina relief workers and regular folks to describe the “leavers” and the “stayers” in three words. The leavers were called independent, self-reliant, responsible, hard-working, conscientious. The stayers, on the other hand, were described mostly in negative terms: Passive. Crazy. Lazy. Irresponsible. Careless. Hopeless. 

Take a dive into the comments section on this NBCNews.com story on Isaac, and the sentiment sounds about the same. Like this one: "What part of MANDATORY EVACUATION do these people NOT UNDERSTAND!" (Bold text and gratuitous use of the caps-lock key are the commenter's own.) Or this: "You were told to evacuate! Now you should be on your own and not expect others to put themselves in harms way!"

In the study, relief workers and others alike acknowledged that many of the stayers might have lacked the financial resources to leave, and yet they still used mostly negative terms to describe them. That disconnect is what Stephens was interested in exploring in the 2009 article, which argues that maybe people who “choose” to dig in their heels and remain in their communities, even when a storm’s a-comin’, actually don’t feel like they ever had a choice. Whether for financial or psychological motives, they're staying. 

 “In retrospect, definitely I was a bit naïve. Natural disasters don’t go by the logic of human psychology,” Cohen acknowledges. “I think that there’s a lot of it that’s hard to conceive – like, it’s hard to conceive of your own death, it’s difficult to conceive of natural disaster. It just seemed unbelievable that another storm could hit the city hard. And so I stayed.”

Keep up with NBCNews.com health editor Melissa Dahl on Twitter.

Related stories:

• More evacuations as Isaac dumps rain on Gulf
• The long road back from Katrina
• Horrible memories for New Orleanians

What if your smartphone were to tell you, “I think you need to see a mental health professional?”

It may sound like the stuff of science fiction, but researchers now say that someday soon our laptops -- and our phones -- might be able to diagnose depression based simply on how we surf the net.

As it turns out, depressed people use the internet differently than others, spending more time chatting online and file-sharing, for example, according to a new study published

The study, which followed 216 college students, monitored actual Internet use and correlated certain patterns with higher scores on depression surveys.

Earlier research looking at the link between Internet use and depression depended on people’s memories of what they did and when, said study co-author Sriram Chellappan, an assistant professor of computer science at Missouri University of Science and Technology.

While that approach has yielded some interesting and important results, it isn’t as precise as one might like.

“If you were asked how many times you looked at your email last month, it would be impossible to give an accurate answer,” Chellappan said.

For the new study, Chellappan and his colleagues asked volunteers to fill out surveys that contained several questions designed to ferret out depression symptoms. The questions were asked in such a way that students wouldn’t realize that the researchers were interested in depression levels, Chellappan said.

Then, the researchers scrutinized study volunteers’ Internet use by monitoring what they did each time they logged on to the university server.

Chellappan is quick to point out that the surveys and internet monitoring were all done anonymously. Each volunteer was given a pseudonym at the beginning of the study and from that point on, they were only identified by their fictitious names.

Chellappan sees the new findings as possibly leading to an early warning system, an alarm that might tell us that we’re becoming depressed.

While other studies have correlated higher internet use with depression, often suggesting that too much time on the computer might actually lead to mental health issues, Chellappan sees these internet use patterns as a symptom.

In fact, he’d like to expand his research to look for associations between internet use and a host of mental health problems. 

Related:

• A blood test for depression? New research points the way
• Sleep breathing problems linked with depression
• Facebook takes a toll on your mental health

Getty Images File

Jill, Ann, and Kimberly go off to college with warnings from their parents about sex and the “Freshman 15” ringing in their ears. Months later, Jill has gained 15 pounds and Ann has become a sexual adventurer. Kimberly, on the other hand, has not only maintained her weight, she's been too busy studying in the library stacks to hook up.

What accounts for the differences?

It could be the way each one’s brain reward center responds to food and sexual cues, reports a new study.

According to research out of Dartmouth College, in some people, hyperactivation of the nucleus accumbens, a key reward structure buried within the brain's striatum, predicted the eating and sexual behaviors of people (in this case, a group of freshmen women).

This suggests one’s ability to say “no” is not just a matter of willpower, but brain wiring.  

The study, published this week in the Journal of Neuroscience, used fMRI brain imaging and pictures depicting food, erotica, landscapes, and people to gauge how the test subjects' accumbens reacted to each stimulus. (The 48 women who completed the study had no idea what it was actually about.)

Six months later, the women returned to the lab where they were weighed and asked to fill out a questionnaire. Those whose accumbens reacted especially strongly to food cues had gained more weight. And those who reacted to sexual cues most strongly were more likely to have had sex and report stronger sexual desire.

Interestingly, their "appetites" did not cross over. The women with hyperactive responses to sex cues did not have a hyperactive response to food and vice versa.

Bill Kelley, associate professor of Dartmouth's department of psychological and brain sciences, says the study shows that the activation of one brain region proved to be a strong predictor of later behavior, demonstrating that the stronger the “liking” response to a stimulus, the less able we are to “hear” our rational brain saying “no.” 

But are we born this way, or do we acquire stronger craving for specific rewards?

“That’s a great question,” said Kathryn Demos, who led the study and is now an assistant professor of psychiatry and human behavior at Brown University.

Kelley thinks that since different women were tempted by different things, their brain wiring has developed through experience, aided by a genetic component.

Luckily, there are tools that can help people blunt the power of their brain wiring. Behavioral therapies, for example, have had some limited success in people who seem strongly stimulated by food. 

People can also try to replace various cravings with something more healthful, for instance, going for a run whenever they're tempted to eat a cheeseburger.

As for the findings, Demos says the idea that all people are equally capable of self-control is naïve.

Reward, she says, “is a very powerful system.”

Brian Alexander (www.BrianRAlexander.com) is co-author, with Larry Young PhD., of The Chemistry Between Us: Love Sex and the Science of Attraction, to be published September 13.

Related: 

• All that stress is shrinking your brain, study finds
• Facebook takes a toll on your mental health

Even though Americans are marrying older, the divorce rate has remained high, a new government report shows.

Centers for Disease Control and Prevention researchers found that the median age for women getting hitched for the first time has risen to almost 26 and to over 28 for men.

Among women there was just a 52 percent chance that a first marriage would survive for 20 years, according to the report from the CDC’s National Center for Health Statistics. Men appeared to be slightly more successful, with a 56 percent chance of a first marriage surviving for two decades.

The older marriage age doesn’t mean that people aren’t getting into relationships – they’re just choosing to live together instead.  “There’s been a real rise in the prevalence of cohabitation,” said the report’s lead author, Casey E. Copen, a demographer with the National Survey of Family Growth at the National Center for Health Statistics.

The percentage of women living with a partner (as opposed to marrying him) has nearly quadrupled from 3 percent in 1982 to 11 percent in the newest survey. The earlier surveys included data only from women so the researchers couldn’t look at whether there had been a change in the rate at which men were choosing to live together rather than to marry.  

The new report includes information from 22,682 Americans between the ages of 15 and 44 who were interviewed in their homes between 2006 and 2010. The researchers also had data from six earlier surveys dating back to 1973 to compare with the new information.

One intriguing finding from the study is that more highly educated people wedded later -- and had longer lasting marriages. Copen and her colleagues found that 78 percent of women with at least a bachelor’s degree had made it to their 20^th anniversary as compared to 41 percent of women with only a high school diploma. Similarly, 65 percent of college educated men saw a 20^th anniversary as compared to 47 percent of the men who hadn’t gone beyond high school.

That falls in line with other new research showing that blue collar folks are less likely to get married than their white collar counterparts, Copen said. “Research has shown that there’s a socioeconomic divide between those who marry and those who don’t,” she added. “People may be more likely to transition to marriage when they feel more economically stable.”

The researchers also found that the lack of a marriage certificate isn’t keeping people from having babies. “A lot of women and men have children while cohabitating,” Copen said.

So, did the new report shed any light on what it takes to stay married? Maybe - depending on how you interpret the results.

For one thing, if you want to stay hitched, you probably shouldn’t choose someone who’s gotten divorced. Looking only at first marriages, just 38 percent of women who chose to wed a divorced man were still married by their 20^th anniversary, as compared to 54 percent of those who wed a man who’d never been married.

Another possible predictor of a shortened wedded bliss: marrying someone who already has kids. Looking only at women in a first marriage, just 37 percent of those marrying a man with kids made it to their platinum anniversary as compared to 54 percent of those who wed a man with no children.

Still, children may indeed be the glue that keeps people together – if they’re conceived and born after the couple marries.

Among women who remained childless just 50 percent reached their platinum anniversary as compared to 77 percent of those who bore children at least 8 months after getting married.

In the end, the report may be telling us something good about the way Americans view marriage.  

Although women are taking longer to decide to get hitched, they are still doing it at about the same rate as they were back in 1995.

Getty Images stock

Adjusting to the daylight saving time switch can be toughest for night owls and people who are sleep-deprived.

For many Americans, the switch to daylight saving time is an annual rite of exhaustion. Gaining that extra hour of daylight at night means losing it in the morning. 

The time shift disrupts the body's natural circadian rhythm, according to sleep scientists. So the alarm clock blares just as your internal sleep-wake cycle orders you to stay snugly in bed. 

It's always harder to adjust to the "spring ahead" time change (as we did Sunday morning) than to the "fall back" change (on November 4), just as it's harder to fly east than west. Circadian rhythms are likely genetically determined and not fully understood. 

But research shows that the natural sleep-wake cycle is slightly longer than 24 hours. Therefore, "the circadian clock prefers us to extend our sleep in the morning when permitted," making it easier to stay asleep later than to fall asleep earlier, said Dr. James Wyatt, a specialist in sleep disorders at Rush University Medical Center in Chicago and a spokesman for the American Academy of Sleep Medicine.  

Genetic traits also determine your chronotype -- whether you are a night owl or a morning lark. Owls tend to have more difficulty with the daylight-saving shift, Wyatt said.

People vary greatly in their reactions to the sleep deprivation prompted by the time change.  Some 70 to 80 percent of people aren't significantly bothered, said Dr. Shyam Subramanian, director of the sleep center at University Hospitals Case Medical Center in Cleveland, and can adjust successfully in a day or two. Others yawn their way through the week.

For them, the consequences can be grave. Rates of workplace and traffic accidents, as well as of heart attacks, rise in the days following the spring time change. One study showed a nearly 6 percent rise in workplace injuries on the Monday after the daylight-saving switch. 

People already sleep-deprived are likely to have the toughest time. "With work, school, family and social obligations, most of us carry a chronic sleep debt into the weekend," Wyatt said. 

Wyatt and other researchers say people then spend the weekend trying to catch up. Even if they go to bed earlier, they can't easily fight their circadian rhythm. So they end up lying awake.

Though some argue that the time change is "just an hour," that amount of time is not insignificant, said Phyllis Zee, a professor at Northwestern University in Evanston, Ill., who is president of the Sleep Research Society. 

People who are nodding off will insist that they are "just resting their eyes," said Zee. "But the data shows they are impaired from an attention and safety standpoint. People are not aware of their level of impairment." 

Sleep experts suggest the following tips to dealing with the time switch:

• Perk up with coffee or another caffeinated beverage in the morning; avoid caffeine in the afternoon and evening.  
• Expose yourself to daylight soon after waking. Doing so helps adjust the circadian rhythm.
• Avoid bright light in the evening. Computer screens mimic daylight and throw your circadian rhythm off. 
• Practice good sleep habits, with a comfy bed, a quiet room and white noise to drown out sounds if necessary. 
• Be especially careful while driving or engaging in other activities requiring full alertness.  

By Stephanie Pappas
LiveScience

Facebook's initial public offering of stock is likely to make a lot of developers and designers of the site very wealthy. But for many users, frequent Facebooking may not be so beneficial.

According to three new studies, Facebook can be tough on mental health, offering an all-too-alluring medium for social comparison and ill-advised status updates. And while adding a friend on the social networking site can make people feel cheery and connected, having a lot of friends is associated with feeling worse about one's own life.

The thread running through these findings is not that Facebook itself is harmful, but that it provides a place for people to indulge in self-destructive behavior, such as trumpeting their own weaknesses or comparing their achievements with those of others.

Take status updates. Most people know that their Facebook friends tend to craft these online-wall memos on what they're up to in a way that puts their lives in the best light, said Mudra Mukesh, a doctoral candidate in marketing at the Instituto de Empresa in Madrid. But when it comes down to actually using the site, reading other people's status updates still makes Facebookers feel worse. [Facebook's Global Reach (Infographic)]

In research presented earlier this month at the annual meeting of the Society for Personality and Social Psychologists (SPSP) in San Diego, Mukesh and her co-author Dilney Goncalves found that when people think about the last time someone asked to friend them on Facebook, they get a boost in feelings of belonging and social connectedness ­— the kind of feeling that makes people "sing 'Kumbaya,'" Mukesh told LiveScience.

But once you've collected all those friends, viewing their status updates is a downer, Mukesh said. When asked how they felt about their place in life and their achievements, people with lots of Facebook friends gave themselves lower marks if they'd just viewed their friends' status updates, compared with people who hadn't recently surfed the site.

For people with just a few friends, viewing status updates wasn't a problem.

"A small number of friends means a low probability of viewing others showing off," Mukesh said. For people with lots of friends, though, the Facebook Newsfeed turns into a parade of good news about other people's live: promotions, engagements, weddings and new babies. Even if someone knows intellectually that people use Facebook to show off, Mukesh said, all of this information can make them feel worse about their own achievements or lack thereof. [10 Technologies That Will Transform Your Life]

(In Mukesh's study, 354 friends was the cut-off point for when participants started to feel bad about viewing status updates. But that's not a universal number, she cautioned, just the number that applied given the statistics of her sample.)

In another study presented at the SPSP conference, researchers at the University of Houston surveyed college students and found that time spent on Facebook is linked to depressive symptoms. That doesn't mean Facebook causes depression, but that depressed feelings and lots of Facebooking tend to go hand in hand, for whatever reason. For young men, the study found, the link seemed to be a tendency to compare oneself with others.

"It appears as if males, when they socially compare themselves on Facebook, they tend to experience depression systems," study researcher and University of Houston doctoral student Mai-Ly Nguyen told LiveScience.

In this case, Facebook seems to be a new medium for men to compete with one another, Nguyen said. Outside the digital realm, men often compare themselves with one another, she said. It may be that women more often use the site to connect with one another and men to compete with one another.

Some people, however, don't use their Facebook status updates to pump themselves up. Instead, they complain.

People with low self-esteem view Facebook as a safer place to express themselves than in face-to-face interactions, according to new research published in the March issue of the journal of Psychological Science. All this venting may actually alienate friends.

Researchers led by Amanda Forest of the University of Waterloo in Ontario collected recent status updates from 117 participants who also reported their average time spent on Facebook and answered questions to reveal their self-esteem levels. Some statuses were chipper, such as "[Poster] is lucky to have such terrific friends and is looking forward to a great day tomorrow!" Others wallowed in bad news: "[Poster] is upset b/c her phone got stolen :@."

Next, the researchers had another group of participants read the status updates and rate how much they liked the person who wrote each. Unsurprisingly, people responded more positively to posters whose updates were positive.

Of course, you'd expect friends to be a little more caring than strangers. So the researchers set up another experiment in which they collected recent status updates from 98 undergraduates and also asked the students to submit the number of likes and number of comments on each.

It turned out that for users with high self-esteem, a negative post garnered more responses than a positive one, presumably because those people's friends were concerned about the out-of-character update. For users with low self-esteem, though, negative posts seemed to exhaust friends: They got few responses.

"Indeed, [low-self-esteem users'] friends rewarded their posts with more validation and attention the more positive they were, perhaps trying to encourage this atypical behavior," Forest and her colleagues wrote.

The takeaway of all this work is not to dump your Facebook account — the site has its benefits, some psychological. But researchers suggest being mindful about your online social life, just as most people are about friends in the real world.

"You have to be careful," said University of Houston psychologist Linda Acitelli, who advised Nguyen on the social comparison study. "I think parents, especially if they have teenage kids, need to be monitoring how much time they spend on Facebook."

Because Facebook provides more opportunities to peer into others' lives, it helps to keep Facebook pitfalls in mind, according to the Instituto de Empresa's Mukesh. She found that reminding people in the moment of what they already know ­— that people brag on Facebook — can ease the self-recriminations that come with hearing about friends' accomplishments.

"At the end of the day, have more friends, there's no problem with that. Just be sure to remember that when you start feeling crappy about your life, think about the fact that you have a large number of friends and that increases your probability of viewing more ostentatious information," Mukesh said. "So, it's not you, it's them."

More from LiveScience: 

• Top 10 Controversial Psychiatric Disorders
• 7 Thoughts That Are Bad For You
• That's an Order! 10 Privacy Tips from the Marines

More from Vitals: 

• All that stress is shrinking your brain, study finds
• Creative types are bigger liars
• Key to erasing a painful memory? Dream on it