Is a coma the only state of impaired consciousness?

A coma is a state of complete unconsciousness in which the person cannot be aroused. There are, however, varying states of impaired consciousness ranging from lethargy brought on by fever or illness, to coma, a state of total unresponsiveness. Stupor is a sleeplike condition requiring extreme shaking and stimulation for a response. Obtundation, like lethargy, refers to a state of cloudy thinking and reduced alertness but no loss of consciousness.