Almost every day, all around the country, volunteers are getting paid for using marijuana, all in the name of scientific research.

Becoming a participant in a study is a lot easier than you think.

With marijuana legalization spreading around the country, more studies than ever are being conducted on the effects of marijuana. Universities and government agencies are all conducting studies, trying to better understand cannabis and its affects on the human body.

What you need to understand is that getting into these studies is often just a click or two way.

Marijuana Research Studies: Federal Database

The National Institutes of Health (NIH) maintains a database of all the ongoing clinical trials across the country, with contact information on each study for volunteers. Simply enter your search criteria – in this case “marijuana” and your location.

As of early June 2017, there are hundreds of marijuana studies in various phases. About a quarter of them are recruiting or about to start recruiting.

All the studies list both inclusion criteria (factors that make you eligible for participating in the study) and exclusion criteria (factors that will keep you out). Some studies test the effects of marijuana on certain conditions and diseases, from HIV and multiple sclerosis to post-traumatic stress syndrome.

However, others are more general in nature and are open to healthy people within a certain age range. They include studies that assess marijuana’s impact on sleep, pain and even how police can find ways to accurately test if a driver is impaired from cannabis

Interested? Here are three of the many studies that are recruiting right now, all listed on the NIH site.

Insomnia in Denver

The Colorado Department of Public Health and Environment, along with National Jewish Health, are recruiting for participants in a study on how marijuana affects insomnia as well as the overall long-term health impact. They are looking for more than 2,000 volunteers – 1,000 who smoke marijuana, 1,000 who use both marijuana and tobacco and 250 who are non-marijuana users.  The age of volunteers can range from 21 to 80. The research will be conducted in Denver.

Driving in San Diego

The University of California – San Diego is conducting a test on the effects of marijuana on driving abilities, and how higher concentrates of THC affect driving. They are recruiting 180 volunteers who will “inhale smoked cannabis” and then be monitored as they drive in a simulation. They also will test whether using iPad-based assessments can determine acute impairment from cannabis. The research, which was approved by the California Legislature, will be conducted in San Diego. The ages of volunteers can range from 21 to 55.

Health Assessment in Seattle

The University of Washington is conducting a six to 12-month clinical trial on the effects of various drugs on health, including marijuana. They are looking for younger adults, ages 18 to 25, who are currently enrolled in college. The trial will test the affect of marijuana on the volunteers’ health, as well as the frequency of use over the length of the trial. The research is being conducted in Seattle.

Those represent just a few of the many choices available. Visit the NIH for more opportunities. New studies are added almost daily, and the site is frequently updated.