Have you talked to your ped about this? If she isn't sleeping much at night and isn't sleeping at daycare, there is a problem.
Is she defiant on other things too? Is there a lot of yelling going on in your home? Are you having trouble controlling her? How do you discipline her?
You need to have calm in your house. When she acts badly, put her in her room and let her cry. Don't stand outside of her room so that she knows she has a captive audience. If she has no one listening to her have a fit, she will stop. After she stops, go in and remind her why she was put in her room, what she was supposed to do instead, and then tell her to say she is sorry for not doing what you asked. (I know some people don't feel that getting a child to apologize is appropriate, but I think that it teaches a child manners, and God knows, we need more of that in this world.) And expect her to do what you asked her to do.
If you do this each and every time she argues or fights with you about other things, she will start to learn that defying you gets her NOWHERE but in her room. You never give in to what she wants when she has a meltdown, she just gets put in her room instead, and after she comes out, she STILL has to do what you told her to do, or she gets put in her room again. And the entire time, you have to be calm, collected, serious, and give NO attention for bad behavior. Just tell her she isn't allowed to do that or she will go to her room. And EVERYTIME, put her there. Never tell her that you are going to do it, and then let her get away with it instead. You must be 100% consistent.
Start this on a weekend. If you have done this all day long, making her understand the rules and how they apply to her, by night time, she will decide to fight you to stay up, to see if she has tired YOU out enough that she can get her way. You must NOT give in. Do a quiet, happy night time routine, snack, bath, brushing teeth, drink of water, potty, read a book, and then tell her good night. Don't listen to ANY "I don't want to go to sleep". Leave her in her room and let her cry. She will eventually go to sleep.
Letting her cry is hard, but this is how you teach her that crying doesn't get what she wants. She is punishing you and punishing herself, and you can't let it go on.
Good luck,
Dawn