I'm barely getting enough sleep tonight. If I go to work I could lash out or have difficulty doing anything. I'be filed for

intermittent FMLA, but this will be the first time using it. I have a new employee that I have no one else to help me train.
But not sleeping can be torture on me at work and I can't imagine coping right now. I'm so ashamed to take the day as FMLA. What will my new employee think about me taking a sick day? Why can't I do what others do and cope when I'm sleep deprived?
I have a brief time to make up my mind. I just feel I can't cope today and need to try to get back on a decent sleep cycle. I'm sick of failing like this. I'm so ashamed of myself.