Your body temperature naturally rises with exercise and sunlight exposure. It also increases when you feel anxious or excited. The human body can withstand lower temperatures more easily when it is warm. A cold body can lead to hypothermia, a life-threatening condition in which the blood vessels constrict, causing insufficient heat loss from the body's core. Eating foods that are hot or spicy, using alcohol or drugs that make you feel sleepy, and having an infection or cancer can also increase your temperature.