sorry I meant it CAN be for several reasons
It can be that you don't rest good even you sleep. And that cant be for several reasons, going late to sleep and waking up late morning for exemple.
There are many reasons you could be so Fatigued. Have you ever been tested for sleep apnea, they say that is good cause for being tired when you wake up.....
You might be lacking certain nutrients, so it might be your diet. If you're not exercising very much, getting more activity could help. But it's my belief that people need one or two days a week to sleep as long as they want so that they get ten or eleven hours those nights. That's what I do, and it really boosts my energy.