1) This is in reference to your Missed periods Q&A. Another cause of missed or late periods is PCOS (polycystic ovary syndrome). A lot of health care providers don't seem to be aware of this syndrome. In this syndrome, missed or irregular periods are caused by unusual hormone levels, sometimes in combination with insulin intolerance. Because missed and irregular periods cause scar tissue build-up in the uterus (which may cause endometrial cancer) and may cause infertility, it is important that your readers know to ask their health care provider about this syndrome. There are obviously other symptoms and complications, but I just thought that I might mention it to you so that you might read up on it for your readers. Thank you.

2) I was recently diagnosed with polycystic ovary syndrome (PCOS). I'm only 17 and am afraid that this will affect my chance of having children. Should I worry? Also, I know birth control pills will help me regulate my period, but if I take them, will it stop the effects PCOS has on me? Like me gaining rapid weight, missed periods, and losing my hair? This is really worrying me. Can you inform me on this syndrome?

1) My problem is this: whenever I have to study late at night, or do anything late at night, I usually have trouble (a lot of trouble) concentrating on whatever it is that I have to do. I'm not going to try anything like No-Doz, but when I drink coffee or anything with caffeine, it just knocks me out even faster. I can't believe it — it's like caffeine's some kind of sleeping potion for me. Some of my friends say eating while you work can help you stay up. I tried that, too. Didn't work. Any suggestions? Or am I just better off sleeping and leaving the work 'till the next day?

2) I am a junior in college. I am pre-med which means I study all the time. However, I can really only focus when I study at night. When I study during the day, it seems that I cannot recall as much information as opposed to studying late at night. How come I can't stay focused during the day? What should I do to help me concentrate during the day?

I find that I'm most alert late at night, and at school I'll stay up till three or four in the morning. Since I've had morning classes in the past, I've tried to form a habit of going to bed earlier — around midnight or one — but realistically, I don't think this is ever going to happen. I was thinking of trying, when I go back to school this fall, to go to bed around three or four and sleep for four hours, and then also take a four-hour nap during the day. Is this a good solution, or will I be more tired than if I sleep eight hours straight at night? Thanks!