Earlier quoted context omitted.
The benefits are sleep, as the article says. I would guess this outweighs the risk that a few students use the opportunity to stay up longer. (although pre 8am seems excessively early to me - we started around 8:50) > I'm particularly concerned that this will incentivize students to just stay up later, negating many benefits of increased sleep. This is missing the point. Teenagers staying up late is often interpreted…
I'm familiar with delayed sleep phase syndrome, is that what you are referring to? You state that it's a symptom of abnormal circadian rhythm, which as far as I know is greatly affected by light exposure. If students are awake later, using their phones/computers, won't that negatively affect their socially acceptable circadian rhythm? I agree that staying up late shouldn't be considered being lazy or disobedient, but…
Hence suggesting that kids will just stay up later is missing the point. The stereotype that kids stay up late partially arises becuase they have shifted circadian rhythms and they can't help it, not that they want to take advantage of later school starts.
And so the benefits of later starts are important becuase it more naturally fits with teenage sleep patterns.
For more info: https://www.ncbi.nlm.nih.gov/m/pubmed/19546564/
> Adolescents continue to show a delayed circadian (or internal clock) phase as indicated by daily endocrine rhythms even after several weeks of regulated schedules that allow for sufficient sleep. This delay is maintained under controlled laboratory conditions in which there is limited possibility for social influence