Open the refrigerator in entrepreneur Dave Asprey's home and you may as well be at a pharmacy.

Every morning he downs a cocktail of about 15 pills, along with his trademark Bulletproof Coffee, which is designed to increase focus. He also squirts a dark-colored goop down his throat called Unfair Advantage, a product he says helps his body metabolize food more efficiently.

He spews names you probably have never heard before: Piracetam, Aniracetam, CILTEP, Methyl, Cobalamin.

Asprey's morning dose is a mix of what's referred to as smart drugs, a broad term for compounds that may increase cognitive function. He also describes many of them as nootropics, which generally refer to natural supplements or nutrients. The terms are often used interchangeably.

The wide umbrella includes everything from fish oil to prescription-only medications like Modafinil, a narcolepsy drug that healthy people sometimes use for the off-label purpose of working all night long.

While many smart drugs are natural and legal, others require prescriptions and are acquired illegally for non-medical usage.

Each one has a different benefit, Asprey, 41, says. One may help bolster memory, another will help you focus. One of his pills helps improve vision, and another promises more energy. They all have the same goal -- to help you maximize your potential.

The idea: mix and match enough of them to find the killer combo; the winning blend is what's known as a "stack." Asprey's stack is ever evolving as he experiments with different ingredients.

After selling his first company for millions, Asprey realized that he was unhealthy and decided to focus on losing weight and maximizing his brainpower.

"When I weighed 300 pounds, I was having really bad problems with brain fog," he said. "As an entrepreneur, that's a problem. I fixed that."

Asprey says he spent 15 years and over $300,000 to "hack his own biology." Along with supplements, he also uses techniques to exercise his brain -- he claims to have increased his IQ by 20 points. His health podcast has been downloaded more than 6 million times.

He now markets and sells some of the supplements he takes. Many of his customers are in Silicon Valley, where the competition is fierce and there's pressure to perform.

More from Sex, Drugs & Silicon Valley

With limited research on long-term effects of smart drugs, much of the experimentation is controversial. But that doesn't stop people, according to Tim Ferriss, a Valley entrepreneur and investor.

"Just like an Olympic athlete who's willing to do almost anything, even if it shortens your life by five years, to get a gold medal, you're going to think about what pills and potions you can take," Ferriss said. "In many people's minds, the difference between completely failing ... and making a billion dollars, is right here," he explained, pointing to his head.

Ferriss is a leader in the quantified-self movement, a group focused on tracking and manipulating what's going on inside their bodies. He says he's tried every class of drugs you can imagine, describing himself as a human guinea pig.

While nootropics are gaining steam, entrepreneurs are capitalizing.

Related: I did LSD with Steve Jobs

Y Combinator, a prominent Silicon Valley accelerator, received a number of applications from entrepreneurs looking to create their own nootropics companies.

"There's clearly consumer demand," Y Combinator president Sam Altman told CNNMoney. "We haven't funded one, we're still getting to understand the space."

There are still many unknowns -- as new stacks crop up, there are reports of new side effects. Online communities on sites like Reddit are filled with discussions of personal experimentation with different nootropics.

"I think that people should follow the Hippocratic oath with themselves: Do no harm," Ferris says. "Rule number one, if you don't know what the side effect is, you're playing in really dangerous waters."

Ferriss warns against taking a handful of smart drugs in the morning.

"It's hard enough to understand the long-term consequences of a newly developed single drug...let alone if you take two, three, or four different drugs together," he said.

Asprey maintains his daily stack is his key to success and continues to live and sell the Bulletproof lifestyle.

"It feels almost seamless, like I just got upgraded...That's a gift," Asprey said.

Sex, Drugs & Silicon Valley:

I did LSD with Steve Jobs

When Silicon Valley takes LSD

I have a fiancé, a girlfriend and two boyfriends