this is smoldering heat in the yin regions of the body. it usually occurs during the later stages of the warm-febrile disease when the heat has depleted the the yin and fluids.

night fevers that recede in the morning indicate heat smoldering in the yin regions of the body. because the yin and the fluids are depleted, the body is unable to generate sweat, which would normally occur as a fever recedes. the fact that the patient does not lose his appetite indicates that the problem is not in the qi level, and that the digestive system is relatively unaffected.

nevertheless, injury to the yin and blood causes a general loss of nourishment and thus emaciation. the red tongue with little coating, and the thin, rapid pulse reflect injury to the yin.

(bensky & barolet)