It's only natural to sweat the phone bill when there aren't enough nickels to rub together. But what explains the millionaire who agonizes over the cost of new curtains, or the homeowner of sufficient means who can't pull the trigger on a long-overdue family vacation?
Indeed, a surprising number of Americans who are otherwise financially secure are quite literally worried sick about money.
A 2015 survey by the American Psychological Association found that money is the leading cause of stress among Americans—especially for parents, younger adults ages 18 to 49 years old and, not surprisingly, those living in lower-income households. For the majority of Americans (64 percent), the survey found, money is a "somewhat" or "very significant" source of stress.
Anxiety of any shade can lead to unhealthy behaviors, such as checking one's online bank accounts compulsively and sleep deprivation, which in turn can cause headaches and high blood pressure.
It can also create tension with loved ones. Almost a third of the adults with partners (31 percent) who were surveyed reported that money was a major source of conflict in their relationship.
Surprisingly, affluent Americans may be particularly vulnerable.
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A 2015 survey of investors with a net worth of $1 million or more by UBS found that while millionaires derive significant satisfaction from the wealth they amassed, they also feel compelled to strive for more, spurred on by their own ambition, the desire to protect their families' lifestyle and an "ever-present fear of losing it all."
"With memories of the financial crisis still lingering, most millionaires don't have enough wealth to feel secure," the report stated.
Half of millionaires with less than $5 million—and 63 percent of those working with children at home—believe that one wrong move, such as a job loss or market crash, would have a major impact on their lifestyle, the survey found.
So what fuels the fear?
In some cases, it's the by-product of income instability. The self-employed, business owners and those who work in industries with a high degree of turnover may be more inclined to worry about their financial future than others, said Masood Vojdani, founder and CEO of MV Financial.
Market volatility, political uncertainty and economic performance, however, can also trigger a money-under-the-mattress response, he said.
"The parents of today's baby boomers lived a Depression-era lifestyle, and they passed that on to their kids," said Vojdani. "We are creatures of habit, and they became savers."
Vojdani recently worked with a client with assets of more than $5 million who was losing sleep over the economic instability in Greece and China. Specifically, he worried (without cause) that the value of his domestic real estate would be negatively affected and that a global economic meltdown would force him to go back to work.
"I often act as a therapist and tell them to spend a little because you are not coming back," said Vojdani. "Enjoy some of this today. My job is to help them live the life they desire without worrying about every little bill."
That requires a plan, he said.
If their primary concern is related to wealth transfer, tax reduction, succession planning or ensuring their children and grandchildren are provided for, Vojdani develops a financial plan to achieve that goal.
But he also coaches clients, especially those of means, to give some away.
"When I ask them how they want to make a difference in the world, it opens their eyes and it takes some of that anxiety away because now they have a purpose for their money," he said.
Some anxiety surrounding money is a good thing, said Lynn Bufka, associate executive director of practice research and policy at the American Psychological Association.
"Worry can often prompt us to rein in spending or reconsider how we are allocating funds," she said. "But if you're adequately funding your retirement plan and saving for your kid's college and you're still completely stressed out and can't stop thinking about it, it's time to step back and determine whether your financial situation warrants that level of concern."
Those who suffer from anxiety, she said, often make connections between things that may or may not be true. One client's husband, for example, refused to let his wife throw a dinner party for his co-workers because he feared he would lose his livelihood if it went badly.
"Some people overpredict negative outcomes and worry that if that bad thing happens, they won't be able deal with it," said Bufka.
When working with clients who suffer from money anxiety, she said, her first step is to take emotion off the table.
She starts by helping them define their fear (e.g., job loss, market crash) and then assess their ability to cope if it did occur.
"What we really want to do is help clients figure out how likely it is that that thing they fear will happen," she said. "If they did lose their job, for example, it's not a given that they would never find another job, especially if they have a solid skill set." Likewise, if the stock market does take a short-term plunge, she might illustrate their ability to ride out the storm by pointing out their emergency fund, personal savings and time horizon until retirement.
Phil Jacobson, managing director at financial advisory firm United Capital, works with several clients who suffer from anxiety. He said the key to keeping money worries at bay is information.
"There are three things that everyone has to have where money is concerned: clarity, confidence and control," he said. "You have to understand what options you have at your disposal, how the decisions you make may impact your personal life and finances and what the trade-offs are for each decision."
If you save a little more or reduce current spending today, for example, what does that mean for your future nest egg? If you retire two years early, how much less will you have to live on?
Asking and answering such questions helps ensure that the decisions you make are right for you and aligned with your personal value system.
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When you understand your options, said Jacobson, you are far better positioned to avoid costly knee-jerk reactions and tweak your financial plan as needed when the unexpected occurs.
"Financial lives are like flight plans," said Jacobson. "There are all kinds of things that will throw us off course, and it's all about the corrections you make to get to your destination."
You may, for example, choose a detour based on changing priorities, or unexpected events such as illness or a job loss may be forced upon you. But having a framework to understand and assess your decisions along the way yields a heightened sense of confidence "because you know you can be back in control fairly quickly," he said.
Another way to alleviate financial stress, said Jacobson, is to reduce or eliminate debt, particularly high-interest credit card balances and car loans.
Other ways to dampen stress, including creating a sustainable budget that liberates you from constant number crunching, getting one month ahead on your bills (so you're not worried about late fees) and maintaining an emergency fund equal to three to six months' of living expenses (up to a year's worth for the self-employed).
Those who manage money stress most effectively don't do it alone, said Bufka of the American Psychological Association.
"Our survey found that people who had emotional support reported less stress," she said. "We encourage people to find an appropriate support network and talk it through." (Hint: If your parents have always judged your spending habits, choose someone else.)
If unwarranted stress over your finances continues to vex, Bufka said it may be time to speak to a therapist or health-care provider.
"If you look at your situation objectively and still feel stressed and overwhelmed and it's interfering with your health, work or ability to function as a parent or spouse, that's a sign that it's time to talk to a professional," she said.
—By Shelly Schwartz, special to CNBC.com