I’m a big "medical drama" fan. I love shows like Grey's Anatomy and House, and when I had my operation in 2010, I told all the nurses I felt like an extra on one of my favorite shows. But I've never actually done anything tangible to help science or save lives (unless you count lifting turtles out of the middles of roads, which of course counts). The truth is, if you’re interested in science and don't mind a bit of extra cash in your pocket for your efforts (who does?!) there’s a lot you can do to help others and earn at the same time. Read on to learn five ways to give and receive with gifts that literally keep on giving.

1. Participate in a research study

Psychologists, psychiatrists, and clinical researchers are always looking for research study participants. Some studies may be non-invasive (for instance, completing a survey or interview) while others may be more invasive (taking medications still under testing or participating in physical tests). Pay can also vary depending on the size of the study, the risks, the time commitment and other factors. Typically, participants can expect to receive between $50 and $300 per day, plus compensation for travel and other expenses.

Note: Even if you go all the way through the study screening process and don't get picked, typically you’ll still be compensated between $25 and $100 just for your time.

Here are common ways to locate studies that pay:

2. Help NASA help astronauts

Would you like to make five figures (as in $18,000)—just to rest for 70 days straight? NASA conducts "bed rest studies" each year to refine and tweak its astronaut health program for astronauts who spend long periods of time in space.

3. Sell eggs or sperm

Not everyone has an easy time conceiving. Many couples struggle for years, trying everything from fertility treatments to surrogates. Some give up, and others keep trying. By selling your eggs or sperm, you give the gift of life—literally.

Donate sperm:

Sperm donors are typically asked to donate for a period of time (say up to six months) and should be in good health with good genetics. You can expect to receive between $30 and $200 per donation. Many banks allow you to donate once per month.

Donate Eggs:

Egg donations are much more strictly regulated—women must meet certain health criteria and be in a certain age bracket to be considered. But if you’re accepted, you can earn between $3,500 and $15,000 per donation.

4. Sell blood plasma

Blood plasma is an essential part of many treatments, including treatments for people with burns, people with blood-related diseases (haemophilia, clotting disorders) and transfusions. When you sell your plasma, you can expect to earn between $20 and $50 per donation, and you can donate once per month.

5. Sell your hair

Selling your healthy hair can help a person who has lost their hair due to cancer treatments or other medical issues, get a beautiful custom-made wig. Your hair may be used in other ways as well depending on what entity you decide to sell it to.  While each entity may have slightly different requirements, generally speaking your hair will need to be at least 10 inches in length, unbleached, untreated and smoke-free.

Places you can investigate to sell your hair (the only sites that don’t charge for posting are listed here):

If you prefer to donate your hair for a good cause:

5 Ways to Help Science, Learn, Earn Extra Cash & Maybe Even Save a Life!