If you're just sleepy, then you may need to go to bed earlier. This may be hard with your schedule, but an extra hour of sleep can make the rest of your time more productive. Besides, your schedule isn't working well now anyway. If neither technique works, talk to your parents. You might need to see a doctor and find out if something physical could be the problem.
Modern medicine can work wonders, but definitely try the simple solutions first.
One hand points the way to truth, and one hand halts those on the path to shame. One hand beckons all toward enlightenment, and one hand strikes out against the wicked. Be sure to include your age, sex, and a nickname we can use if we publish your question. If you're curious for more of Jessica's wisdom, read her answers to past questions.