Coca-Cola would like consumers to believe that happiness can be bottled up in just 12 fluid ounces (355 milliliters) of sugary goodness. The company's soda ads pair its products with the most enjoyable times in life -- neighborhood cookouts, movie dates and hanging out with near and dear ones. In Africa, this Coke-happiness correlation may have more behind it than just marketing dollars. In times of war and political strife in recent years, Coke sales have dipped; when stability returned, so did the soda consumption [source: Economist].
Monitoring someone's Coke consumption isn't the most scientific way to gauge happiness. But the Africa anecdote is an example of the relationship between emotional states and behavior. It's well understood that our feelings often affect actions. Confidence, for instance, breeds socialization, and apathy fosters withdrawal.
Interpreting the emotions behind the exhibitions isn't always simple. When asked, most people will concede that they're happy [source: Soltis]. They may not be over the moon in rapture, but they're far more likely to describe themselves as at least slightly happy than as unhappy. At the same time, the National Institutes of Health report that about 6.7 percent of adults in the United States deal with major depressive disorder.
While you can't equate depression with run-of-the-mill unhappiness, there does seem to be a disconnection between reported and actual happiness. In that case, certain behaviors signal that negative emotions are taking a toll. After recognizing them and taking action, folks can get back on track toward joy.
Sometimes, a stressful day simply calls for a night of indulgent television. Kick back, relax and let your mind melt in the sea of reality shows and hospital dramas. But if this is your routine night after night, it may be wise to abandon the remote for a while. According to a 2008 study, excessive boob-tube time is a possible sign of unhappiness.
Since 1972, researchers at the University of Chicago have conducted the General Social Survey to evaluate the social climate in the United States. Regardless of education, income, marital status or age, happier people surveyed watched about 30 percent less television each week than unhappier participants [source: Bryner]. On average, the happier respondents watched 19 hours of television, compared to 25 hours for the unhappy set. Instead of kicking back on the couch, take a cue from the happier lot. Their leisure time involved hanging out with friends, volunteering or participating in organized activities.
A sure sign of growing despondency is fractured relationships. Unhappier people may have more difficulty resolving issues or project immediate problems onto the future. They may not attempt to broaden friend circles and meet new people. And when relationships turn sour, this can reinforce feelings of discontent.
The happier people included in the General Social Survey spent more time with others in one way or another. That result echoes throughout the vast body of happiness research; consistently, those with the deepest and widest social connections report the highest levels of life satisfaction. For instance, surveys demonstrate that married people are generally happier than singles. Yet, happier folks may be more likely to get married in the first place.
Reaping the benefits of bonding with friends and family can happen through online social media as well. The Virtual Happiness Project, which is evaluating the relationship between happiness and online social networking, has so far found that building relationships via online platforms can boost happiness [source: Mollman].
Some behavior issues scream unhappiness. If you're constantly stressed or finding that all your close relationships have turned rocky, you're probably already aware that trouble is looming. But sometimes the signs you're not doing so hot are subtle. A small change in your personality might signal that something deeper is going on.
Shying away from new experiences -- or even finding a lack of satisfaction in the experiences you originally found positive -- can leave you feeling quite negative about your circumstances. A University of Missouri study that quizzed 481 people about their happiness showed that participants who were able to appreciate a life change or a new experience for longer had a generally happier outlook [source: Wall].
This is also true for happiness in marriage or relationships. Couples who share novel experiences long after they've been together report greater marital happiness than couples who find their relationships routine. Simply participating in fun activities together, it turns out, makes us think of our partners (or perhaps even ourselves) as fun [source: Gordon].
There's a reason why doctors immediately put you on the scale when you visit. Weight changes are extremely indicative of how our bodies are faring physically, and the effects of unhappiness and depression can show themselves through appetite.
While for a long time we assumed that being overweight could make you more depressed, there's also some evidence that being depressed makes you gain weight (or at least gain abominable fat.) In a study conducted over 15 years, 5,115 men and women between 18 and 30 years of age took a survey every five years to assess depressive symptoms. The study held a surprising result: Those who had a higher BMI didn't get more depressed over time. But those who did report depression gained more belly fat as time went on [source: Needham].
Even more, there's now evidence that a healthy diet -- vegetables, fruit, whole grains, the whole shebang -- resulted in a lower occurrence of depression. About 2,000 middle-aged or older Finnish men took part in a study that surveyed both eating habit and depressive symptoms. Study participants with a high intake of processed and junk foods showed more prevalent depressive symptoms [source: Ruusunen]. So if you find that you're not so interested in feeding yourself well, you might be struggling with more than just proper diet.
According to positive psychology, or the science of subject well-being, environment plays an important role in people's quest for happiness. Feeling safe and comfortable generates contentment and satisfaction. Conversely, an excessively stressful environment promotes anxiety and insecurity. For instance, a study comparing controllable and uncontrollable stress found that the latter caused greater unhappiness and tension [source: Breier et al.]. While stress compels us to work more efficiently and achieve greater goals, too much of it can adversely affect long-term happiness.
One recent example of the stress effect is the paradoxical shift in happiness among American women in the past 35 years. Despite the progress women have made in recent decades, their rates of subjective well-being have declined overall [source: Stevenson and Wolfers]. Researchers have attributed this to the rising stress levels women must manage while juggling a family and career. A separate comparison of how people spend their time concluded that men may be happier today because they spend less time on unpleasant tasks than women [source: Leonhardt].
While we can't entirely eliminate stress from our lives, some tenets of positive psychology can help alleviate it. Specifically, positive thinking, mindfulness and optimism serve as emotional stress antidotes. When stress strikes, fight the urge to park in front of the television and try out relaxation techniques instead.
No, we don't have to panic every time we find ourselves screaming at the drawer in the kitchen that constantly sticks or snapping at a friend on a bad day. Irritability comes up in the normal course of life.
But it turns out that having overt irritability and anger during a depressive episode is a significant indicator that a strong or persistent depression will occur [source: Judd et al.]. One 31-year-long study led by University of California San Diego scientists indicated that people -- even those who didn't have more episodes of major depression before the study -- who had displays of irritability and anger were more likely to later have chronic, severe depressive episodes as time went on [source: Brooks]. Now note that it wasn't just an occasional crabby day that put a person in this group. Subjects had to acknowledge that they were "somewhat argumentative," "quick to express annoyance," would often lose their temper or shout, or were even "repeatedly violent" [source: Healy].
Even more interesting, those with irritability and anger also had a higher rate of anxiety disorders and substance abuse. The study's authors even suggested that depression that featured irritability and anger might be diagnosed and treated differently than your run-of-the-mill major depressive disorder [source: Healy]. If you do find yourself far more prone to irritable or even hostile behavior, there's a chance you're not just unhappy -- you're depressed.
In the late 1970s, a team of psychologists led by Philip Brickman came to a startling conclusion about humans and happiness. In comparing the happiness levels of a group of lottery winners and a group of paraplegics to that of the general population, the psychologists discovered that both life-altering events made negligible differences on the groups' well-being after a while. The researchers attributed this phenomenon to the adaptive functioning of the human spirit. Given time, people will acclimate to circumstances, whether fantastically positive or negative.
In the case of the lottery winners, a sudden jolt of wealth didn't improve their happiness in the long run. Instead, people can get trapped on what Brickman coined a hedonic treadmill, or an endless search for bigger and better material goods to bring pleasure. The problem with this pathological pleasure-seeking is its intrinsic emptiness. By definition, pleasure is momentary and fleeting -- leaving us wanting more. Contentment, on the other hand, means appreciating present circumstances and surroundings.
Most of us would understand that when we're really not feeling hot, we don't get very hot either.
Interestingly, sex is tied to happiness in a surprising number of ways. It's hard to say if not having sex makes someone unhappy, but we can point to several studies that indicate having more sex leads to a more positive outlook [source: Alexander]. There was even a 2002 SUNY Albany study that showed that women who had unprotected sex had lower levels of depression than women who used condoms or abstained from sex [source: Abbasi].
A University of Colorado Boulder professor also released a paper that used national survey data to find that those who had a higher frequency of sexual encounters reported a happier outlook in general [source: University of Colorado Boulder]. He also saw that no matter how often people reported having sex, if they thought they were having sex less than their peers, they reported lower happiness.
So not only a lack of sex drive, but also a perceived lack of sex might be a trigger that you're not doing so hot, emotionally.
After a night of tossing and turning in the bed, you finally nod off to sleep. Moments later -- or so it feels like -- the alarm chimes, and it's time to get up. Needless to say, this isn't the best way to start the day. A study published in the journal Science tracked 909 working women's mood shifts throughout the day. Aside from work-related stress, not getting enough quality sleep was the top predictor of unhappiness among the subjects [source: Carey].
Also, a psychology professor at the University of Michigan calculated the happiness boost people get from sleeping an extra hour each night as equivalent to receiving a $60,000 annual raise [source: Barnett]. This impressive effect likely relates to brain chemistry. The brains of sleep-deprived people are more sensitive to the effects of cortisol, a stress hormone [source: Franklin Institute].
The link between sleep and happiness begs the question of correlation versus causation. Does poor sleep make us unhappy, or is unhappiness hindering sleep? It probably depends on individual situations. Someone working 60 hours per week may be suffering from overwork and sheer lack of sleep time. On the other hand, symptoms of unhappiness, such as stress and television, don't promote quality rest, either.
Tackling the sleep issue may require a multipronged approach. Evaluating stress levels and exercise routines are smart places to start. After all, when you don't prepare your body for bedtime, nodding off can prove challenging no matter how happy you feel.
On the flip side of a failure to sleep is an equally insidious sign you're not doing so hot in the mental health department: You could sleep all day and still never feel like a well-rested human being. About 15 percent of people with depression sleep too much, which can be detrimental to keeping a healthy schedule [source: Ratini]. People who sleep for longer had a higher mortality risk, as well [source: National Sleep Foundation].
Certainly, fatigue is well-recognized as a symptom of depression, and it can persist even after the depression is successfully treated [sources: Targum, Fava]. But weirdly, total sleep deprivation for one night (or missing an entire day of sleep that isn't made up) relieved depressive symptoms in 40-60 percent of treatments [sources: Giedke, Schwarzler].
Of course, this isn't to say that the cure-all for feeling blue is watching the all-night marathon of the reality show about polygamous families. Because that can really depress a person.