Everyone requires different amounts of sleep. The 8 hours is just an average.
As you age, the quality of sleep diminishes so you generally need longer hours to get the same rested feeling you had on less sleep as a child.
I now need 9 hours most nights or get sick easily and am just not as sharp as when fully rested.
Get what your body needs and don't worry about it. If your 180 was there even when rested, your Dr. might be right, otherwise ignore the...