Debilitating fatigue, cognitive impairments (such as inability to concentrate, forgetfulness, or confusion), or a combination of other signs and symptoms:

Which are nearly constant and so severe as to restrict routine daily activities almost completely and which may occasionally preclude self-care

Which are nearly constant and restrict routine daily activities to less than 50 percent of the pre-illness level, or; which wax and wane, resulting in periods of incapacitation of at least six weeks total duration per year

Which are nearly constant and restrict routine daily activities to 50 to 75 percent of the pre-illness level, or; which wax and wane, resulting in periods of incapacitation of at least four but less than six weeks total duration per year

Which are nearly constant and restrict routine daily activities by less than 25 percent of the pre-illness level, or; which wax and wane, resulting in periods of incapacitation of at least two but less than four weeks total duration per year

Which wax and wane but result in periods of incapacitation of at least one but less than two weeks total duration per year, or; symptoms controlled by continuous medication