I know you are in the states but some websites we use here in the UK may help you, I will add them at the bottom for you.
I am unsure of your age (eighth grade), so forgive me but i will do my best.
OK so even if you didnt, you should have started revision friday evening, just for 1 hour. (note this for next time)
Then an hour of your essay - Just an hour of each.
Rest of your friday night or whatever evening it is is yours.
Then Saturday another hour of each.
Sunday day hour of revision and learning lines for Midsummer nights dream.
Sunday evening relax.
See what I did? You just got to keep on top of your work. start it in the class (if you get enough notice), and start it straight whhen you get home from school so you can have the rest of your night to yourself.
You said your up past midnight, is that cos you have loads to do for school, or do you leave things to the last minute? I used to leave stuff and do it a panic but i soon learnt if i did it when i got it i could get it out the way!!!!!
If you really have too much work, you need to speak to your tutor or form teacher.
I suffer with nightmares. I still do now and I am not even 30 yet. I have had them all my life!!! Try drinking camomile tea before you go to bed .
It will relax you and hopefully if your relaxed you can have less nightmares.
I always recommend Valarian root you can buy it in health food shops, supplement shops, or online. Is a natural sedative (herb) and is used to treat anxiety and insomnia.
Why dont you have a text book? You need to speak to your maths teacher and let her know this!!!!! She will understand.
I know its hard but you need a study diary plan so you can plan when your doing what homework and when.
This site has some good study advice;
http://www.bustertests.co.uk/studies/tips-for-studying-for-gcse.php
http://www.s-cool.co.uk/default.asp