The possible cause could be that even though you sleep 9 hours,(average adult requirement is 7-8 hrs) you may not having deep sleep.
There are 5 phases of sleep. In simple terms Phases 1 and 2 are light sleep and 3 and 4 are deep sleep. The 5th phase is dreaming stage. If you lack the phases 3 and 4 which are deep sleep, you are likely to wake up tired even after sleeping enough time.
There could be various reasons. 1. Depression
, 2. Fibromyalgia(associated with muscle pains), 3. Obstructive sleep apnea(associated with overweight
Please have an MD evaluate you in his office and seek further management after diagnosis.