I suffer from extreme sleepiness too. My whole day revolves around napping. Our brains clearly needs rest and quiet.

I really hope you are able to sort something with your job so you can take some time off, stress free. As mark said...please do NOT drive under ANY circumstance. Somebody's poor judgement/lack of attention/sleepiness meant I got into a horrible accident and now I'm like this. Even if it means upsetting your boss, your life and others' lives are worth more than that. Promise??