Those risks include heart palpitations, nervousness, loss of appetite and trouble sleeping. And then there is the risk of addiction. “You teach yourself that you need a pill to be able to study. That is problematic,” says Van der Horst. People with ADHD are also supervised by their GP, who lacks guidance among the students who use the medication without a prescription. “The doctor monitors what works and in what quantity. These students are actually experimenting with their own brains.”