Aside from the issues raised in the article:
* Make sure they don't have an environmental problem interfering with their sleep, such as an unsafe or noisy home.
* Make sure they don't have a physical problem interfering with their sleep, and that they don't have sleep inertia.
* Check their natural biorhythm. If it's on a greatly different setting than their current school, provide education according to their body clock. Forcing them to work in the middle of their body-night is ruinous to health and doesn't teach them much anyway.
* Provide interesting material and plenty of activity during the day. Inactivity and boredom can put even well-rested people to sleep. This is most likely an issue if many students are sleepy.
* A tremendous cause of not getting enough sleep is too much homework. Limit or better yet eliminate homework; schools have 8 hours a day and any more than that constitutes an unreasonable infringement on "8 hours for work, 8 hours for rest, 8 hours for what we will" of a healthy balanced life. And of course, if students don't get enough sleep because they have too much homework, they tend to do a shitty job in school anyway.
* If they're falling asleep in school, for fucksake let them sleep. Lack of sleep can kill people. Also, sleep deprivation is a recognized form of abuse and torture. Go figure out what the problem is, and after you've fixed it, they'll stop falling asleep in class. If it's unfixable, leave them the fuck alone.