I have probably bored you with several posts kvetching about the side effects of beta blockers, particularly the extreme chronic fatigue making me quite breathless after climbing a flight of stairs. A few weeks ago, I was dragging myself out to do chores--shopping at Costco. My cell phone rang and one of my doctors instructed me to get my rear end to the Emergency ward because he had just received lab results of blood work and my hemoglobin was "dangerously low".
I received 2 units of blood and have been getting inter-venous iron infusions since. The change in my fatigue was immediate and dramatic (I can now climb the stairs without breathlessness--merely a slight rise in heart rate.)
So I now add anemia to my sleep apnea and my heart arrhythmia, all of which can contribute to a symptom of "chronic fatigue". Sorting out the right things to do to get some energy is ever more complex.
Be sure you do not slip into this situation.