On work The work you do by choice and that consumes your mind at all hours of the day is the work that you should make your full-time gig. That's a long-term goal because it's not feasible at the moment, but you can find a way in the future. In the meantime, you have to be more efficient about your working time so as not to appear a workaholic. I can't say that you have an unhealthy love for work—it's just what you enjoy doing, this whole writing thing. When people ask you what you do for fun, you should say this. That's not to say you should do nothing else, but this shouldn't be too much of a burden. However, I never want you to remove the label of work from what you call your writing hobby. In order to turn it into a full-time venture, later on, you have to treat yourself and act like a professional. Hold yourself to deadlines and manage your projects like you would have to if you did this for a living. Don't restrict yourself, of course, but don't let yourself become a starving artist because you don't have the discipline to hone your craft day in and day out. This is your job, whether you get paid to do it or not.
On being tired Tired is sometimes a convenient label for you to be in a poor mood, but most of the time the tired precedes the mood. The effect of your sleep on the rest of the day is more than tangible, and you have to acknowledge that as you grow tired later in the day. The best route is not always to power through and continuing to labor. 15 minutes of shut-eye would benefit you far more in the long run. The only reason you don't do it is that you are too vain. You are worried that you will look lazy or like you don't want to work by taking a nap. This isn't regulated to your behavior in the workplace—even in your own home, when nobody is around, you force yourself to stay awake and continue to work. Is your God going to condemn you for having slept to continue being industrious? I would hope not—do what you need to do and if you are so unfocused because you are exhausted, then to hell with your work. Get focused. Without focus, attention, and intention, you are useless. Don't continue until you've solidified those three.