This is a tiny part of the brain located at the forebrain, right above the pituitary glands. This tiny body regulates temperature control, thirst and sleep. It collects data from other parts of the brain and sense organs through nerve impulses. It acts as the link between the nervous system and the endocrine system.
The hypothalamus monitors the temperature of the blood that passes through it to detect any change in the body temperature. It also receives information about temperature changes in the external surroundings from thermoreceptors messages sent from the skin.
This is because chemotherapy targets rapidly-dividing cells throughout the body, aiming at the cancer but also affecting the healthy cells that produce hair on the scalp and all over the body.