What is your night time sleep quality like? If you sleep 10 hours and still feel tired, ask your doctor about an overnight sleep test which measures O2 sats while you sleep, and ALSO the sleep phases e.g. non-REM and REM. Night sats and day sats can differ a lot, and affect your sleep quality. My day sats are great and FEV1 around 70, but my dipping night time sats kept my body from going into all the sleep phases. I feel a million times better sleeping with 02 now. I can actually make it through a day without feeling like a zombie by mid afternoon.Good luck , let us know if you solve your tired-mystery