Students are mimicking ADHD symptoms in a bid to get their hands on a drug that can help them improve their concentration.
Ritalin is most often prescribed to sufferers of attention deficit hyperactivity disorder (ADHD). But a handful of young adults have also been using it as a "brain booster" to give them an edge over their competition.
The white circular tablets contain the stimulant methylphenidate and work by activating parts of the brain that allow concentration, "dimming" others.
For a child with ADHD, Ritalin stimulates the production of dopamine - the brain chemical involved with motivation - and helps them to focus on the task at hand.
For the average youth, it boosts their concentration power, tuning out the "white noise" often blamed for procrastination.
The Straits Times spoke to six former and current Ritalin users, who said the drug is favoured by those in reading-intensive university courses and jobs requiring prolonged concentration periods.
Whole chapters of textbooks can be read in a third of the time, and number-crunching tasks whizz by, they said.
Most such Ritalin takers do not actually have ADHD and rely on friends who have the drug - or even imitate symptoms to a psychiatrist.
Though the number of abusers is believed to be small, one said she is "not the only one who takes Ritalin" for purposes other than ADHD.
"A small circle" of classmates take it to cope with examinations, said the 23-year-old graduate student, who declined to be named.
She claimed such pill-popping has been going on for at least a decade. "Many of us found out about the drug from our seniors."
The practice also takes place in the United States, Europe and China, where experts have expressed fears of a "Ritalin generation".
Not all hospital and private psychiatrists, and even fewer general practitioners, dispense Ritalin, and the health authorities say they can do so only under strict supervision.
The pills must be kept under lock and key. Names of those who purchase them, as well as the quantity they buy, must be recorded.
Practitioners told The Straits Times that they try to avoid dispensing Ritalin altogether, preferring less addictive alternatives.
If they do so, it is in conjunction with long-term counselling.
To prevent abuse, psychiatrists have implemented a series of checks to ensure young adults claiming to have ADHD are not doing it to get Ritalin.
Most ADHD cases are diagnosed during childhood, said Dr Chan Herng Nieng of Singapore General Hospital.
When anyone over 19 comes in claiming they have ADHD, he requires that they bring their report book and, in some cases, their parents to verify their academic history.
"You can't claim to be perpetually inattentive but score As all the time," he said.
Another 23-year-old student, who was diagnosed with ADHD by a private psychiatrist three years ago, admitted that she "probably doesn't need" Ritalin and takes the pills only in the weeks leading up to her exams.
Even if abusers get around such checks, financial obstacles may stand in the way.
One user said her doctor's consultation fee alone costs $400, while each pill costs $2.
One 27-year-old banker told The Straits Times that his "supplier" is a friend diagnosed with ADHD. He takes his pills during "more intense trading days" to "shut out the anxiety and focus on closing deals".
He has taken the pills since his last year of university.