It is among the worst-kept secrets on college campuses: Come finals time, a growing number of undergrads are turning to Adderall and other so-called study drugs to enhance their concentration.

More often than not, the medications are brought to campus by students with a prescription. But they work their way into the hands of other students, some seeking the focus needed for an all-night study session.

The drugs are safe for individuals being treated for attention deficit hyperactivity disorder, said Dr. Eugene R. Hershorin, a professor of clinical pediatrics at the University of Miami Miller School of Medicine and a practitioner at Holtz Children’s Hospital at Jackson Memorial.

But for those who aren’t?

“If the person has underlying cardiac diseases, the medications can actually be very dangerous,” Hershorin said. “They can also worsen depression and anxiety, and lead to things like insomnia.”

Attention deficit hyperactivity disorder, or ADHD, is a developmental disorder that affects an individual’s ability to sit still and focus. Symptoms include hyperactivity and impulsiveness.

The disorder is found in about 14 percent of children, or about 10.4 million, according to a study published earlier this year in Academic Pediatrics. Boys are about three times as likely to be diagnosed as girls. That figure represents a dramatic increase from the 6.2 million children who had the disorder in 2000.

Experts say the spike occurred because pediatricians became better trained in mental health and developmental issues, and the disorder became more socially acceptable.

The number of children being treated with medication has also spiked.

“There was a cluster of patients who had clearly recognizable signs and symptoms that could be verified by family practitioners and psychiatrists, that warranted the proper use of stimulant medication,” said Dr. John Eustace, associate medical director of the South Miami Hospital Addiction Treatment Center.

In 2007, the Centers for Disease Control and Prevention estimated that 2.7 million were receiving medication to treat ADHD.

Stimulants have been used for treatment since the 1930s. There are two types: Amphetamines like Adderall and Vyvanse, and methylphenidates like Concerta and Ritalin. The medications are thought to work by increasing the levels of chemicals like dopamine and norepinephrine in the brain, stimulating attention.

Doctors say the drugs are generally safe, and tend to help patients over time. But problems arise when the medications are taken by individuals who don’t have ADHD.

That’s exactly what’s happening on college campuses.

Some college students see Adderall as a recreational drug. Some even grind it and snort it like cocaine.

“Adderall being an amphetamine can be a club drug,” Eustace said. “You stay up longer. You dance faster. You drink more.”

Other young adults use the medication to enhance their academic performance.

“Kids can take them at night and it helps them stay awake and study,” said the University of Miami’s Hershorin.

But like most controlled substances, Adderall and the other study drugs can have side effects.

When the drug wears off, a person may experience a period of low energy and depression. Because Adderall is also an appetite suppressant, the person may become voraciously hungry when coming off of the medication.