I don't have time to read all of the replies, but I just have a few things to say. Medical school is not the hardest thing you will ever do. I personally found the first year easier than any of my years of working. I socialized, cooked, and exercised more than I ever had in my post-college life of working 2 jobs. I think you have an adjustment period--like anything else--and then you figure out what you need to do, and then nobody dies (except maybe your patients!). So doing crazy things like stopping your period or whatever are not necessary. We do have to live for, like, the next 70 years after all. Nothing can be THAT impossible to reconcile with our daily lives.
Having said that, it's good to freak out for the first couple of months so you get solid grades and can ease back gradually. Better to take it seriously at first than to have to repeat a class or a year. But very very few people fail classes/years, most of us do just fine with plenty of balance in the first year.