anita ko from drexel medicine, she specializes in sleep issues.hanks so much for being here, both of you. anita ko: thank you. rick tony: thanks for having us. erin: all right, so rick, let's start with you. what differences have you seen since you pushed back those start times? rick: we've seen a difference in terms of student's wakefulness, as you would expect. but other things, like an increase in students attending breakfast, being ready for--we serve breakfast every morning. being ready for class, and generally a lower stress level. still teen anxiety, there will be some of that obviously, but a reduction in that as well, without losing any of the academic standards or what we need to do as a school. really i've seen very few, if any, downsides to starting at 8:30 instead of 8. erin: hmm. so, dr. ko, what factors make it hard for teens to get the sleep that they need? anita: well, the research has shown that, you know, as teenagers get older, there's a naturally occurring hormone in our bodies called melatonin, and in teenagers, this hormone