My 13 year old baby boy has been sleeping a lot more than usual. I took him to the vet and he could not find any signs of illness. He checked for diabetes and kidney disease and did a checkup. He does eat and drink normally but most of the day he prefers to sleep. I don't understand why. I will add, he has been molting but in the past he never napped this much during molting. He has always been a healthy cockatiel, never been sick and I pamper him a lot. I am worried.