Maybe money can't buy happiness. But not having money can certainly make you feel like crap. And, as new research suggests, having enough to get by can make a huge difference in how you feel about your life — and yourself.For the study , published online last week in Health Economics, researchers went all the way back to the '90s, before the U.K. implemented a national minimum wage. To do so, they used data from the British Household Panel Survey, which included socioeconomic information for 5,500 households from 1991 to 2009. They were particularly interested in those surveys filled out right before and after the national minimum went into effect in April 1999. The researchers compared this to data from another national survey, the General Health Questionnaire, which asked about blood pressure, smoking, hearing ability, and mental health.To figure out how the minimum wage affected people's health, the researchers looked at the surveys in three groups: Those whose wages increased in April 1999, those whose wages didn't increase because they were already earning an amount equivalent to the new minimum wage, and those who were eligible for an increase but didn't get one because their employer didn't comply.Results showed that, after the national minimum wage went into effect in 1999, only those who got a wage increase showed better scores on mental health. Those who stayed at the minimum wage and those who stayed below the minimum wage did not see the same improvements. And there was no boost in terms of the other health-related measures — only mental health improved."Our results indicate that increasing wages is likely to improve mental health," write the study authors, "for example, by reducing depression and by alleviating financial strain among low-paid workers." In fact, the researchers found that the improvement in particpants' anxiety and low mood were comparable to what they'd expect to see if they had prescribed antidepressants to a group of people with depression.The study was published to coincide with the introduction of a new living wage in the U.K. , but the U.S. is having its own minimum-wage conversation. And this study is a good reminder that we're talking about a whole lot more than dollars.