Do a sleep study. Any number of hours can be insufficient if you have sleep apnea, as the body is not getting the rest it needs. I had the same problem. Using

Do a sleep study. Any number of hours can be insufficient if you have sleep apnea, as the body is not getting the rest it needs. I had the same problem. Using a CPAP since over 2 years now, and it has been life changing. The effect wasn't evident overnight for me and I think I am still recovering from decades of lack of proper sleep due to the apnea.