Colorado  |  Wills and Trusts

My Uncle is in hospice with cancer and he is termanel. He has stated that he wants his mom to take care of his money and put it in her bank. He is very alert and aware. The Dr. says he can still make and comprehend financial and medical decisions. He is on morphine. Can he sign a Power of Attorney? Would his signature be considered legal, due to he is on the morphine?

Thank you for your time.