> While what you say is true, does pushing the start time of class back 30 minutes or 1 hour make any difference? I'm skeptical.

Did you read the article? They have done several studies to show a significance difference in academic performance with a slight shift. That's the whole reason for this change.

"One three-year study (pdf, p.1) of 9,000 high-school students across three states, for example, found that academic performance, “including grades earned in core subject areas of math, English, science and social studies, plus performance on state and national achievement tests, attendance rates and reduced tardiness show significantly positive improvement with the later start times of 8:35 AM or later.”