Feeling alternating sensations of being hot and then cold is a common experience. These shifts often involve chills, sweating, or a general feeling of discomfort. Understanding these fluctuations helps demystify why the body reacts in such ways, as they directly reflect the body’s internal systems attempting to maintain a stable core temperature.
How Your Body Regulates Temperature
The human body maintains a stable internal temperature through thermoregulation. This process is primarily orchestrated by the hypothalamus, a region in the brain that acts like the body’s thermostat. The hypothalamus constantly monitors blood temperature and receives signals from skin temperature receptors.
When the body’s core temperature drops, the hypothalamus initiates mechanisms to generate and conserve heat. These include shivering, which produces heat through rapid muscle contractions, and vasoconstriction, where blood vessels near the skin constrict to reduce heat loss. Conversely, if the body’s temperature rises too high, the hypothalamus triggers responses to cool down. These mechanisms include vasodilation, which widens blood vessels to increase blood flow to the skin and release heat, and sweating, where sweat evaporation helps dissipate heat.
Why Your Temperature Fluctuates
Temperature fluctuations arise when the body’s thermoregulatory system responds to internal or external stimuli. A common cause is the body’s reaction to an infection, leading to a fever. During an infection, pyrogens, substances released by immune cells or microbes, signal the hypothalamus to raise the body’s temperature set point. As the body works to reach this new, higher temperature, individuals may experience chills and shivering, feeling cold even as their internal temperature rises. Once the infection subsides or medication takes effect, the hypothalamus resets the temperature to normal, and the body cools down through sweating, leading to a sensation of feeling hot.
Hormonal shifts also influence body temperature. Women experiencing menopause often report hot flashes, sudden sensations of intense heat, particularly in the upper body and face, followed by sweating and sometimes chills. These flashes are linked to fluctuating estrogen levels, which can affect the hypothalamus’s thermoregulatory control. Pregnancy can also lead to temperature changes due to increased metabolism and hormonal shifts. Thyroid imbalances, such as hyperthyroidism (overactive thyroid), can cause increased heat production and intolerance to warmth, while hypothyroidism (underactive thyroid) may result in feeling consistently cold due to a slowed metabolism.
Stress and anxiety can also disrupt the body’s temperature regulation. When experiencing stress, the “fight or flight” response activates, releasing hormones like adrenaline and cortisol. These hormones can alter blood flow, constricting vessels in some areas and dilating them in others, potentially leading to sensations of warmth or coolness. This response can also increase metabolic rate, temporarily raising body temperature.
Environmental factors influence temperature fluctuations. Rapid changes in external temperature, such as moving from a warm indoor environment to a cold outdoor one, can trigger the body’s immediate thermoregulatory responses, like shivering or sweating, to adapt. Inadequate clothing or a sudden cold draft can also prompt the body to react by conserving or dissipating heat.
Some medications can interfere with the body’s ability to regulate temperature as a side effect. Certain drugs, including some antidepressants, antihistamines, and decongestants, can affect the hypothalamus or alter sweating mechanisms. This can lead to increased heat retention or excessive sweating, causing unexpected shifts between feeling hot and cold.
Underlying health conditions can also manifest as temperature dysregulation. Anemia, characterized by a lack of healthy red blood cells, can lead to individuals feeling consistently cold due to reduced oxygen delivery and poor circulation. Blood sugar imbalances, particularly hypoglycemia (low blood sugar), can affect the body’s energy production and metabolic rate, sometimes causing symptoms like sweating, chills, and weakness.
When to Consult a Doctor
While occasional temperature fluctuations can be normal, consult a doctor if the sensations of feeling hot then cold are severe, persistent, or worsening. This includes instances where fluctuations interfere with your daily activities, sleep patterns, or overall well-being.
It is also important to consult a healthcare professional if these temperature shifts are accompanied by other concerning symptoms. These might include unexplained weight loss, extreme fatigue, difficulty breathing, persistent pain, changes in skin appearance like a rash, or any new, unusual symptoms. If there is no clear cause for your temperature fluctuations, or if you suspect a more serious underlying health condition, a medical evaluation can help determine the root cause and guide management.