Hey Enzo, When your doctors checked your blood, did they check your iron levels? People with CF are notoriously have low iron levels. My clinic usually only checks iron when I am on IV's, otherwise not. A few years ago, I had a major complication with anemia (my hematocrit/red blood cells were half of what they should have been) and I had a blood transfusion. I started taking iron everyday. I asked my primary doctor to write me a standing order to get my iron levels checked, which I do every other month. Taking iron daily has made the biggest improvement in my energy level. I used to take 3-hour naps daily, now sometimes I don't even need a nap and occasionally have insomnia. Just remember if you start taking iron, you need to get your blood levels checked and make sure your primary doctor knows.