According to the article, caffeine improved the ability to stay awake and attend a task. Many people believe that it may help to concentrate on something to do, so they eat coffee or tea which contain caffeine. From time to time, some people drink more coffee to perform what they have to do better. That means this would be true for most of the people to stay awake and have more concentration.
Nowadays, many people have a tendency to rely on caffeine to concentrate on their tasks. I am also that kind of person. When I attended a lecture a few years ago, I experienced severe drowsiness when I didn't drink a coffee in the morning. On next day, I stopped by a rest area and bought a cup of coffee to supply some caffeine in my body, and I didn't feel any drowsiness during the class. So, I agree that caffeine can reduce the effects of sleep deprivation.
However, it affects on simple tasks generally. The research found that caffeine had little effect on how people performed in the more difficult tasks. The more important thing for the sleep is to have a sufficient sleep time. Most people should get more than 7 hours of sleep per night. But, in Korea, most of students suffer from lack of sleep because of hard study such as after-school academy. That causes a vicious cycle for them not to concentrate on their class in the morning. That would be one of the reason for students not to take classes with concentration.