You mentioned taking iron pills that anemia might be an issue? Have you been checked lately w/ a GP to be sure it isn't something physical going on? I have bouts of anemia too which can wreak havoc on energy levels in an of itself.

I know for me this time of year depression is an issue with the shorter days and change in the weather, the gray, rainy days. I do tend to start sleeping more and have to watch for depression if there is no sign of anything physical causing it. I have to increase an anti-depressant that I am already on if so. If you aren't taking anything or have considered it, and there are no physical ailments (they have been ruled out), I would talk to a GP or pdoc for help to head this off with an anti-depressant but that is just me.

If not interested in meds or to use in addition to meds in the meantime:
I have found walks and getting some fresh air to help. If can get other exercise, it can be beneficial though I know difficult to be motivated for this. The doc also recommended as the days get shorter a light therapy box by Verilux, (or any that are at least 10,000 lux) 30 minutes in the morning 14-18" from you off to the side (never look directly at them), helps too.

I don't know if this helps but I understand your frustration and the draining feeling you describe for whichever reason that is causing it. Hang in there in the meantime. Will be thinking about you.