I don't think many people will be able to relate but here's my post anyways.
I was always a procrastinator. By high school senior years, I received only 1-3 hours of sleep on a frequent basis. My study habits were very terrible. I would come back home at 3:30 PM and I would try to force myself to start and for some reason I couldn't start until 7:00 PM. It kept getting worse - while I previously was able to start at 7:00 PM, soon I could only start until 8:00 PM, 10:00 PM, midnight, 1:00 AM, 3:00 AM, 4:00 AM. I would frequently take Tylenols to stop the massive headaches. I sometimes considered suicide by overdosing on those pills. In hindsight, I am so happy that I didn't kill myself and looking back at it, I can't believe I was so irrational. I actually asked for help here but the moderators were no help (they closed my thread and redirected me to a suicide hotline but there was a reason why I was avoiding the hotline... it wasn't their fault though as this is a physics forum and I'm a random Internet stranger).
Lots of people will tell you that procrastination is normal. Do not listen to them. It might be natural for humans to procrastinate but do not mistakenly think that because procrastination might be considered natural or normal that it is healthy. If there is one thing I regret is that I wish I recognized that I have a serious issue earlier in time. It always seemed like my colleagues were in the same boat as me. It always seemed like my peers were procrastinating just like me and that prevented me from taking steps to alleviate my procrastination.
Anyways, it has been a couple of years since I've graduated and I'm currently taking double the workload I had in high school. I have almost no problem managing the load. For 6 days a week, I start at 9:00 AM and finish at 4:00 PM - 5:00 PM. It feels so relieving to be able to finish in the afternoon and to have the rest of your day to do whatever you want. Here is the book I used:
http://www.amazon.com/dp/0767922719/?tag=pfamazon01-20 You're probably skeptical and I actually don't mind at all if you don't take this advice. In fact, if your issue isn't severe, then it's probably best that you ignore this post. However, if you are ever into a situation like I was, where you are considering suicide, then in addition to getting mental help, I seriously recommend you consider this book because it turned my life around.
EDIT: I just realized that you never said that you had a problem with procrastination. I'm an idiot to assume you did.
EDIT2: You're a junior in high school and you're doing Laplace transforms already. Now I'm almost positive that my advice doesn't apply to you.