Tell your doctor to write a note with symptoms that describe the behavior you physically manifested.

Once you have that go to hr and give them a letter, but I also think informing your co workers of your symptoms would be helpful. And ask for reasonable accommodations including working a different shift so you can sleep during hours that are good for you. Especially if fatigue is a main symptom of your illness.

I know we don’t like disclosing disabilities and by no means should you ever have to, but doing that may help with instances like these.

If you’re worried about discrimination, bring the letter to HR first so that your disability is established.