It was his freshman year in college and Jon Burnes* had let studying slide. He had a paper due the next morning, and his only hope was to stay up all night and write it in one straight shot. The trouble was that Burnes had slept only a few hours in the prior nights and could barely keep his eyes open. When he complained to his roommate about his dilemma, a solution presented itself: A friend offered Burnes some Ritalin that he had mooched from a classmate with ADHD. Although he had never tried it before, he knew that many students casually popped these study buddies with no apparent ill effects. So he popped the pill and waited.

Fifteen minutes later, he felt electricity coursing through his body and was overcome with a burning motivation to finish his paper. He worked feverishly until dawn, finishing his paper just minutes before the deadline, then crashed when the pill wore off, content now that his work was done. The only downside, he figured, was that he almost slept through class.

Whether to gain an edge, stay awake, or get high, 16 percent of university students say they have abused ADHD medications such as Ritalin and Adderall. Of those, 40 percent say they crush and snort the pills. Some even distill the drug in water, "cook" it, and inject it, to get a more rapid, intense high.

In a normal, healthy body, dopamine is continuously being synthesized and broken down. But when stimulants such as cocaine, Ritalin, or Adderall are introduced into the body, they slow the degradation process by inhibiting the neuronal membrane protein responsible for initiating it. Production continues unabated and dopamine levels rise, overloading the brain's pleasure systems. Over time, excessive dopamine exposure can impair the brain's ability to regulate the hormone on its own.

There is less risk of overloading the dopamine level in people with ADHD, explains Stanislav Svetlov of the University of Florida, because their dopamine levels are extremely low to start with. "There is no free lunch with any drug," stressed Scott Teitelbaum, a medical director at the Florida Recovery Center. "And when you take a drug without a prescription, you're rolling the dice." Adderall and Ritalin can cause death in people with undiagnosed problems, such as a heart condition, says Richard Kadison, chief of Harvard University's mental health services and co-author of College of the Overwhelmed. Anyone taking these medications, he advises, should do so only under the supervision of a doctor monitoring them for side effects such as disturbances in heart rate, sleep, mood, and appetite.

Over time, continued use of ADHD medications can make you less effective intellectually, due to the poor mental functioning caused by insomnia, addiction, or malnutrition. Meanwhile, the paranoia, aggression, and irritability that often accompany these drugs may make you less successful socially. Heart failure and lethal seizures are rare, but are more likely when drugs are snorted or injected.

Students who take these steroids of studying tend to score worse than those who have worked diligently all semester, says Teitelbaum, who is also a professor at the University of Florida. He also notes that college is a time to figure out your preferences—if you feel you can never concentrate on math homework, maybe it's time to try another subject. If you are having trouble focusing in general, make sure you're getting adequate sleep, exercise, and food. And talk to your doctor.

* Name has been changed.