Should I WhatsApp my mom to let me sleep?

So, I have to get up in 5.5 hours, and I'm really not feeling well. I just threw up a little. I've been lying awake the whole time and can't sleep because I feel so sick. I don't want to wake my mom, but I don't think I can go to school like this. I'm thinking about just writing to her so she can check me out if she reads it, or should I wait until I get up and tell her in person? I'd actually rather sleep through the night if I do fall asleep.