<p>Well, you still have time to consider, but based on what I've read, you'd probably want to cancel. On the bright side, you know what not to do next time. And yes, sleep is quite essential; I probably missed a math question because of a lack of concentration that I assume was brought about by a lack of sleep.</p>
<p>masha,
when my son was doing his SAT practice, taking the test awake and alert vs. tired and sleep deprived made made about a big difference per section - about 70 points on math and 50 on verbal. He had to retake the old writing test - his was sleepy going into it, drank too much pop, focused more on peeing than writing. He needed that score for an early action application, otherwise he would have cancelled. He retook the next opportunity, scored 120 points higher, and rushed the scores to his colleges.</p>
<p>The fact of the matter is that you have plenty of time to take and retake your SAT and SAT II's. You're just going to be living, breathing and eating SAT's for the next nine months. And you as you keep taking them, you will get better at taking the test, and as you mentioned in an earlier post, make sure you are not taking the test sleep reprived. Good luck whichever path you take.</p>