For centuries, philosophers have been searching for an answer to what makes us happy. But perhaps more interesting is what's scientifically proven to make us unhappy. It wouldn't take a genius to work out that tiredness, stress and loneliness are lead causes. But more surprising candidates include living at altitude and poor sibling relationships. Or who would guess that the end of your favourite TV show could lead to all-out misery, let alone a wandering mind?
Come check out the ten unusual factors that have been empirically linked to feeling low:
If you're addicted to checking status updates on Facebook every two seconds, it may be time for a breather. A study by University of Michigan psychologist Ethan Kross last year found a direct correlation between time spent on the social media site and feelings of dissatisfaction, loneliness and isolation.
His team sent text messages to eighty-two residents in the Michigan town of Ann Arbor five times per day over a two week period, asking about their feelings at any given point and their use of Facebook. They discovered that the more people used Facebook in the time between the texts, the less happy they felt.
"On the surface, Facebook provides an invaluable resource for fulfilling the basic human need for social connection," said Kross. "But rather than enhance well-being, we found that Facebook use predicts the opposite result - it undermines it."
Other studies have backed up these findings, blaming the "compare and despair" envy effect of social media sites and their potential to spark jealousy and suspicion in relationships.
And it's not just social media, but the internet in general that could be the risk; a 2010 study in the US found "a small detrimental effect of internet use on psychological well-being."
Lisa Kelly, a Toronto-based psychotherapist, says she has observed the way in which social networking is linked to depression and anxiety.
"People have lost the ability to be honest with each other about their feelings, insecurities or needs," she says. "They often do not know how to authentically connect with themselves and with others."
Too much money
Obviously, money is important to lifestyle and well-being - especially when it comes to eliminating financial stress. But studies that show that beyond a certain threshold of income, where people are comfortable and don't need to worry about paying the bills, money doesn't have much connection to happiness.
In fact, some research has shown that very wealthy people actually suffer from higher rates of depression. A World Health Organization survey from 2010 interviewed 89,037 people in 18 countries and found that depression was more likely to hit those living in high-income countries than poorer ones (France was highest with 21% occurrence of depression, next to 6.5 percent in China, the lowest country).
It's unclear why richer countries experience higher rates of depression. The study's authors suggest a greater inequality of wealth in those countries, but other research has indicated that a desire for wealth and material possessions is linked to a need to mask inner discontent. And a continual striving for greater wealth and more possessions leads to unhappiness, because we cannot satisfy or change the reasons behind that desire.
"No matter how much we try to complete or bolster our ego, our inner discontent and incompleteness always re-emerges, generating new desires," reads a paper by psychology lecturer Steve Taylor. "No matter how much we get, it's never enough. As Buddhism teaches, desires are inexhaustible. The satisfaction of one desire just creates new desires, like a cell multiplying."
Instead, we need to aim to make enough to live a comfortable life and then focus on social connections, says scientist Tyler Cowen.
"A threshold earner is someone who seeks to earn a certain amount of money and no more ... in order to experience other gains in the form of leisure -- whether spending time with friends and family, walking in the woods, and so on."
Lack of control at work
A study by a Danish university last year found no link between workplace depression and heavy workload. Instead, said researchers at the Department of Clinical Medicine at Aarhus University, work environment and the feeling of being treated unfairly by management can most dramatically alter an employee's mood.
The researchers handed out questionnaires to 4,500 public employees at Danish schools, hospitals, nurseries, offices and more. They found perceived unfair treatment led to a higher rate of the stress hormone cortisol, which in turn can make work assignments appear insurmountable. But the depression in itself is caused by management behaviour and work environment, rather than workload.
"When the employees’ sense of justice plays such a central role in minimising the risk of depression, this is probably the area that the preventive work should focus on," says psychologist Matias Brødsgaard Grynderup, PhD, leading the study.
"I recommend a management style in which there is a clearly expressed wish to treat employees properly – combined with a transparent organisational structure."
Dr. Greg Couser, M.D., the medical director of the employee assistance program at the Mayo Clinic in Rochester, Minnesota, has also observed that employees with more control enjoy a greater work life - regardless of how demanding their jobs are.
"In general, you can have a demanding job and if you are able to have control over factors such as the work pace it can be more manageable," he says. "But if you are at the bottom of an assembly line and things are coming at you at a rapid pace you don't control, eventually you can't keep up."
Too much choice
Choice is a buzzword of the modern age, whether that's five types of organic honey in your local supermarket or a string of pilate classes to select from at the gym down the road. But a 2010 research paper from Stanford University's Department of Psychology discovered that too much choice makes us miserable.
Scientists at the university looked into the cultural ideas surrounding choice. They found that freedom and choice are less important or mean something different among non-Western cultures and working-class Westerners than they do for the university-educated people. They also found that the latter group became paralysed by too much variety and wracked with uncertainty and regret about whether they had made the right decision.
"We cannot assume that choice, as understood by educated, affluent Westerners, is a universal aspiration, and that the provision of choice will necessarily foster freedom and well-being," Professor Hazel Rose Markus writes in Does Choice Mean Freedom and Well Being?
"Even in contexts where choice can foster freedom, empowerment, and independence, it is not an unalloyed good. Choice can also produce a numbing uncertainty, depression, and selfishness."
A famous jam study conducted by Colombia University in 1995 also concluded that choice can be debilitating. In the survey, people were made to select from a larger or smaller selection of jams in a gourmet Californian supermarket. A larger proportion of people (60%) went for the larger selection, but only 3% from that group went onto actually buy a jam. In the smaller selection group, 30% of people went onto choose and buy a jam; suggesting too much choice can be bewildering.
Similar studies conducted over the years with everything from chocolate to speed dating have reached similar conclusions.
Poor sibling relationships
Anyone who's grown up with brothers or sisters will know that fights are inevitable and usually harmless in the long-run. But a 2007 study in the American Journal of Psychiatry found that men who had very poor relationships with their siblings during childhood are at significantly greater risk for depression in adulthood, compared to those who get along better with their brothers and sisters.
The researchers emphasised that their findings do not mean that a poor childhood relationship with a sibling causes depression, but they concluded that the two factors are strongly associated, and sibling relationships are more of an influence on adulthood depression than how a child is brought up by their parents.
"Sibling relationships have been underemphasised in learning about child development," says Dr. Robert J. Waldinger, the lead author of the study.
It's not clear why the link exists but researchers believe that good sibling relationships in childhood could help children socialise and relate to their peers - and the opposite could be true if they do not have good sibling relationships.
In 2012, psychologists at the University of Missouri concluded that teenage siblings who argue over two topics in particular - personal domain conflicts and fairness issues - are more at risk of suffering depressive symptoms, low self-esteem and anxiety.
"We believe that there are particular types of conflict that are setting kids up for problems," says Nicole Campione-Barr, assistant professor of psychological sciences at the University of Missouri.
A wandering mind
We all like to daydream now and again, but a 2010 study from Harvard researchers Matthew Killingsworth and Daniel Gilbert identified mind-wandering as a major cause of unhappiness.
The researchers collected data from 2,250 volunteers, who used a specially developed iPhone app that contacted them randomly to ask how happy there were feeling, what they were doing, whether they were thinking about what they were doing, and, if not, whether they were thinking about something pleasant instead.
They discovered that our minds are wandering about 46.9 percent of the time in any given activity and that people's feelings of happiness had much more to do with where their mind was than what they were doing. Only 4.6% of a person's happiness could be attributed to what they were doing, but 10.8% of it was caused by what they were thinking about at the time, and people consistently reported being happiest when their minds were on what they were doing.
To investigate whether unhappiness caused mind wandering or vice versa, the Harvard psychologists compared each person’s moods and thoughts as the day went on. They found that if someone’s mind wandered at 10 in the morning, then quarter of an hour later that person was likely to be less happy than at 10, perhaps because of daydreaming. But if people were in a bad mood at 10, they weren’t more likely to be worrying or daydreaming at 10:15.
"We see evidence for mind-wandering causing unhappiness, but no evidence for unhappiness causing mind-wandering," the report found.
The findings are backed up by age-old philosophy that living in the here and now leads to greater happiness.
"Many philosophical and religious traditions teach that happiness is to be found by living in the moment. These traditions suggest that a wandering mind is an unhappy mind," Killingsworth and his team note.
The end of your favourite TV show
The prospect of no more Breaking Bad is a bit gutting, one might think, but it's hardly a cause for serious unhappiness.
However, Emily Moyer-Guse, PhD, assistant professor of communication at Ohio State University, has found that people form ''parasocial" relationships with their favourite TV shows and "experience distress" when they end or are taken off air.
Moyer-Guse surveyed 403 college students ages 18 to 33 during the 2007-2008 Hollywood writers' strike, when many shows were taken off air. The students answered questions about their viewing habits, reasons for watching, how important the shows were, and how close they felt to their favourite characters.
Those who watched TV to relax, to enjoy the companionship of the characters, or to escape pressures were more distressed, she found, that those who said they watched TV just to pass time. Those who watched for companionship were most likely to be distressed.
Jeffrey Andrew Weinstock, PhD, professor of English at Central Michigan University, who reviewed the study, says some people invest a lot of their time in TV shows and when they disappear, "it's like you have lost someone important to you. It does leave a hole there for a while. It's a form of mourning."
This chimes with reports of the Avatar effect in 2010, when there was said to be an outbreak of depression among some viewers of the film because the utopian planet created in it was not real. After the Harry Potter franchise ended in 2011, a number of fans reported feeling similar levels of unhappiness and desertion.
Eating junk food
Countless studies have linked poor diet with depression, including a 2012 paper published in the Public Health Nutrition journal. Researchers at the University of Las Palmas de Gran Canaria and the University of Granada studied the eating habits of 8,964 participants who had never been diagnosed with depression over a six-month period.
The results revealed that those who regularly consumed commercial fast food (hamburgers, hotdogs, doughnuts and pizza) are 51% more likely to develop depression, compared to those who eat little or none.
A dose-response relationship was also observed, meaning "the more fast food you consume, the greater the risk of depression," explains Almudena Sánchez-Villegas, lead author of the study.
"Although more studies are necessary, the intake of this type of food should be controlled because of its implications on both health (obesity, cardiovascular diseases) and mental well-being."
Critics pointed to a link between depression triggering junk food consumption, as well as vice versa, but it does seem there is an intrinsic link between junk food and depression - even down to the logos used on popular brands of junk food.
In 2013, a study published in the Social Psychological and Personality Science identified a link between the occurrence of fast food logos in participants ' neighborhoods and a decreased capacity among those participants to savour and enjoy pleasant experiences. It concluded that fast food symbolism reinforces our chronic impatience and precludes people from finding happiness on their own, as we have a harder time "stopping to smell the roses".
Over-analyzing your decisions
Worrying about whether you have made the right decision can be a maddening, no-win process so little wonder that researchers have linked questioning decisions with stress and unhappiness. In 2011, Dr. Joyce Ehrlinger and her team at Florida State University identified two types of decision makers: "maximizers" - individuals who obsess over decisions (big or small) and then fret about their choices later and "satisfiers"; those who tend to make a decision and then live with it.
"Maximizers get nervous when they see an ‘All Sales Are Final’ sign because it forces them to commit," Ehrlinger, whose study was published in the journal Personality and Individual Differences, says.
"Maximizers show less commitment to their choices than satisfiers in a way that leaves them less satisfied with their choices. Maximizers miss out on the psychological benefits of commitment."
As it affects every decision from shopping goods to choice of a life partner, this lack of commitment and contentment can be a huge cause of stress and uncertainty over a long-term period.
"Identifying the ‘right’ choice can be a never-ending task (for a maximizer)," Ehrlinger and her co-authors write.
"Feelings about which option is best can always change in the face of new information. Maximizers might be unable to fully embrace a choice because they cannot be absolutely certain they chose the best possible option."
Living at high altitude
Life in a mountain village might seem idyllic but it's also been linked to a higher rate of suicide. A 2011 study by medics at the University Hospital Case Medical Center in Cleveland, Ohio, found a correlation between suicide rates and higher elevation residency in places such as Nevada, Utah, Colorado and Montana in the US.
"Once you get to somewhere between 2,000 and 3,000 feet, you start seeing the suicide rates increase," explained study author Dr. Barry E. Brenner. "The correlation is very, very, very high, and it happens in every single region of the US."
"And yet as you go up in altitude the overall death rate, or all-cause mortality, actually decreases," he added. "So, the fact that suicide rates are increasing at the same time is a really significant and really striking finding."
Brenner and his team studied two decades' worth of mortality data (1979-1998) obtained from the U.S. Centers for Disease Control and Prevention. They related the higher suicide rates to obesity levels and sleep apnea that may be more common in higher altitudes, as well as hypoxia -- inadequate oxygen supply to the body's cells and tissues at high altitudes - that may trigger mood disturbances, especially among emotionally unstable patients.
Another survey by the university of Utah found similar results in the US and two other mountainous countries, Italy and South Korea.
"South Korea has a very high suicide rate, first or second highest in the world, and South Korea has a tremendous range in altitude from sea level up to several thousand metres," says psychiatrist Perry F. Renshaw, leading the study. "We found the same thing there. The higher the altitude, the higher the suicide rate."
Words: Anna Brech, Photos: Rex Features