When you need to pay off debt, you need money. And if your 9-to-5 isn’t paying the bills then you have to get creative.

One of the easiest ways to earn real cash and do some good in the process is to participate in medical research studies. The medical community is constantly on the lookout of human guinea pigs for a wide variety of behavioral and clinical tests.

Graduate students have long taken advantage of this cash cow, and you can too.

If you live in a university town (or near any major metropolitan area) then the odds are good that you can find some money-making opportunities close by. But what are these trials, and are they safe?

That being said, you do need to be wary of scams. Anyone who asks for cash upfront from you needs a swift kick in the nether region and a hearty goodbye from you. Legitimate medical programs almost never ask for a financial contribution from their subjects.

A good place to start your research is with the website ClinicalTrials.gov. This site is a registry and database offederally and privately supported clinical trials that are legitimate and provides contact information for those running the trials.

Of course the big question is how much you can earn. That depends on how much time the researchers are asking and how invasive the program is. You can earn a few hundred dollars up to several thousand.

Now don’t get your hopes up too high; you won’t qualify for every program. Most have specific requirements for their volunteers, with a nod towards younger, healthier applicants. But many programs are looking for people truly suffering from specific diseases or conditions.

So if you have a lot of free time and even more expensive debts, this may be something to explore.