It's typical. Depression can be caused by hormones, so does your period, it's all connected. I don't want to come into details, b/c of my poor english but I know that many girls and women experienced that phenomenon.

Nicoel - Degrassi-Yotch's mother was right in some sense - if you're really nervous about your period it can really have a serious delay. Stress is one of the most common period-deferring factors.