If you’ve long struggled to dial in your attention at work or are currently suffering from a bout of brain fog, you might want to check out a class of supplements known as nootropics before throwing in the towel on feeling clear-minded and productive ever again. Read on for the details, including what they are, how they work, and how to begin supplementing for yourself.

Nootropics Defined

Nootropics are a subcategory of supplements that boost cognitive functioning. These substances, often called “smart supplements” and “cognitive enhancers,” can promote concentration, increase energy levels, support memory, and improve creativity and motivation, says Dr. Josh Axe, D.N.M., C.N.S, D.C., founder of Ancient Nutrition and member of The Vitamin Shoppe Wellness Council.

When taken by athletes, nootropics may also improve performance by narrowing focus and improving reaction time, adds functional medicine expert Dr. Jordan Leasure, D.C.

Read More: What Causes Brain Fog—And What Can You Do About It?

Intriguing, right? And while nootropics support pretty specific goals, there is a whole slew of natural nutrients and compounds that are included in the category. “’Nootropic’ is broadly defined,” says Leasure. In fact, it includes everything from B vitamins and omega-3s to plant extracts like artichoke leaf extract and cat’s claw extract. It also includes caffeine and other common pre-workout ingredients like l-theanine, creatine, and beta-alanine, adds Axe.

Some prescription drugs, specifically those formulated for conditions like Alzheimer’s, narcolepsy, ADD, and ADHD are also categorized as nootropics, says Leasure.

Nootropics vs. Adaptogens

If you’ve heard of adaptogens, another popular category of supplements, you may be wondering how nootropics differ.

Axe explains: Adaptogens are herbal supplements designed to help the body combat stress and maintain equilibrium. “Typically, adaptogens are calming and balancing, while nootropics have the opposite effect and are stimulating,” he says.

Read More: The Best Adaptogens For Every Wellness Need

That said, it is possible for a supplement to be classified as both an adaptogen and a nootropic. Energizing ashwagandha and vitalizing Maca root, for example, fall under both. “There is overlap between categories,” says Leasure. So, don’t get too caught up in the name game.

So How Do Nootropics Work, Exactly?

According to Axe, nootropics work by altering levels of certain neurotransmitters, enzymes and/or hormones in the brain, such as acetylcholine, adrenaline, dopamine, serotonin, and GABA. “The exact effect of the specific supplement depends on what it does to levels of neurotransmitters, hormones, and other chemicals in the body,” he explains. So, you’ll want to do a little research on the specific nootropic supplement you’re interested in to learn exactly how it works.

Are Nootropics Effective?

Prescription nootropics have been proven to work for the people they are designed for and prescribed to. Methylphenidate (Ritalin), for example, effectively supports people with ADHD, while Auxura has been shown to help treat symptoms of Alzheimer’s disease.

Research on non-prescription nootropics is more limited, although promising. One 2016 review published in the journal Evidence-based Complementary and Alternative Medicine concluded that natural nootropics, such as Gingko Biloba, may support cognitive function, particularly in people with memory issues. Studies have also shown promising results for people without serious memory concerns, too. One review, for example, found that ginseng may help enhance attention, while another study concluded that l-theanine may increase alertness and focus.

That said, supplements can only do so much, according to Leasure. “You can’t out-supplement bad habits,” she says. “Nootropics can’t compensate for a poor sleep schedule and eating habits, or non-existent exercise.”

Are Nootropics Safe?

“Nootropics are usually non-toxic and non-addictive and are generally safe when taken in the proper amounts,” Axe says.

However, factors like what specific nootropic someone takes, how much they take, and how often they take it all affect its safety level, he says. Some people may experience side effects like nausea, stomach upset, dizziness, sleep disturbances, restlessness, headache, and pins and needles when taking nootropics.

Additionally, since non-prescription supplements aren’t regulated by the FDA in the way that drugs are, it’s important to purchase from brands that have undergone independent third-party testing through organizations such as NSF, USP, and the Banned Substance Control Group. Neuriva, Onnit, and Plant People are three great brands to consider.

How To Supplement With Nootropics

Specific ingredients that qualify as nootropics can be taken as stand-alone supplements. (Think: vitamin B12, fish oil, and ashwagandha.) However, it’s far more common for multiple nootropic ingredients to be combined into a single supplement. “Combining multiple types of nootropics enables the supplements to work most effectively,” says Leasure.

To figure which nootropics to take and/or stack, Leasure suggests working with a nutritionist or holistic health practitioner. “A healthcare provider will be able to match the nootropics to your symptoms and desired effects,” she says. They’ll also be able to make sure you’re not supplementing with any ingredients that will interfere with prescription medications you may be taking. (Certain herbal supplements have been shown to impact the effectiveness of medications.)

Exactly how much of each nootropic you should ultimately take varies from person to person and supplement to supplement. “Unfortunately, there is no one-size-fits-all guide to supplementing,” says Leasure. If you’re interested in giving nootropics a whirl, sign up for a free consultation with one of The Vitamin Shoppe’s credentialed nutritionists to learn more about which might work best for you.