While The Sun-Herald revealed yesterday that some students had been taking their peers' ADHD medication to improve their focus, many others are popping pills legally.
Excessive consumption of caffeine pills, coffee and energy drinks are common, students sitting exams told the Herald.
Ishan Shekher from Crestwood High School takes two caffeine tablets every three to four hours on days he lacks energy. He also relies on energy drinks ''when I get bored of caffeine tablets''.
The Department of Education says schools have stringent rules about the administration of drugs, as has the NSW Board of Studies.
The 2012 HSC rules and procedures state a student must not "attend an examination while under the influence of alcohol or illegal drugs", on penalty of failure.
The Dietitians Association of Australia says a little bit of caffeine is OK but too much can be counterproductive.
''They can get anxious and nervous. It can affect their concentration. It's certainly going to stop them sleeping well, so over time it will make them fatigued,'' a spokeswoman, Kellie Bilinski, said.