Feeling both hot and cold can be a confusing experience. The human body maintains a remarkably consistent internal temperature through a complex process known as thermoregulation. These fluctuating sensations often signal this sophisticated system is actively working to maintain balance or responding to various internal or external stimuli. Understanding these responses can shed light on why your body sometimes feels caught between two temperature extremes.
The Body’s Internal Thermostat
The brain’s hypothalamus acts as the body’s central thermostat, monitoring and adjusting internal temperature. It receives signals from temperature sensors throughout the body, integrating this information to maintain core body temperature within a narrow, optimal range, typically around 37°C (98.6°F). When the body deviates from this set point, the hypothalamus triggers specific physiological responses to either generate or dissipate heat.
One primary mechanism involves the circulatory system through vasodilation and vasoconstriction. When the body needs to cool down, blood vessels near the skin surface widen, increasing blood flow to allow heat to escape. Conversely, when the body is cold, these blood vessels narrow, reducing blood flow to the skin and conserving heat within the core. This dynamic blood flow can directly contribute to sensations of warmth or chill.
Another heat-generating response is shivering, involving involuntary muscle contractions. These rapid movements produce heat as a byproduct of energy expenditure, helping to raise core body temperature when it falls too low. To cool the body, sweat glands release perspiration onto the skin, and as this moisture evaporates, it carries heat away from the body, leading to a cooling sensation. These coordinated actions ensure the body’s temperature remains stable despite external changes.
Common Triggers and Responses
Environmental shifts are a straightforward reason for experiencing temperature fluctuations. Exposure to cold environments triggers the hypothalamus to conserve heat through vasoconstriction and generate it through shivering, causing chilliness. Conversely, hot environments prompt vasodilation and sweating to release excess heat, causing warmth. These are the body’s direct and observable attempts to adapt to its surroundings.
Infections and illnesses frequently cause fevers and chills. When the immune system detects pathogens, it releases substances that effectively “reset” the hypothalamus’s temperature set point to a higher level. The body then perceives itself as cold at its normal temperature and initiates heat-generating responses like shivering to reach this new, elevated set point, causing chills. Once the fever breaks, the set point returns to normal, and the body works to cool down, often leading to sweating and a feeling of being hot.
Stress and anxiety can also influence body temperature perception. The “fight or flight” response, triggered by stress hormones, can cause changes in blood flow and metabolism. This can lead to sensations such as cold sweats or hot flashes, as the body’s physiological arousal impacts its ability to regulate temperature. These temperature shifts are a physical manifestation of the body’s stress response.
Other Contributing Factors
Hormonal fluctuations often disrupt the body’s thermoregulation. During menopause, decreasing estrogen levels can affect the hypothalamus, narrowing its thermoneutral zone and causing hot flashes—sudden feelings of warmth, often accompanied by sweating and sometimes followed by chills. Pregnancy also involves hormonal shifts, which can cause a slight elevation in core body temperature and make individuals feel warmer than usual. Thyroid imbalances, like hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid), directly impact metabolism and can lead to increased heat production and heat intolerance or decreased heat production and cold intolerance, respectively.
Certain medications can have side effects that interfere with temperature regulation. Some antidepressants, blood pressure medications, or even over-the-counter drugs may affect the nervous system’s control over blood vessels or sweat production, leading to unexpected sensations. These effects vary significantly depending on the specific medication and individual response.
Nutritional deficiencies, such as anemia, can also contribute to feeling cold. Anemia, often caused by iron deficiency, reduces the red blood cells’ ability to transport oxygen. This can impair overall metabolic processes, including heat generation, making individuals feel persistently cold, particularly in their extremities.
Underlying medical conditions that affect the nervous system’s control over involuntary bodily functions, known as the autonomic nervous system, can manifest as temperature dysregulation. Conditions like dysautonomia can impair the body’s ability to control sweating or blood vessel constriction, leading to heat or cold intolerance and unpredictable sensations.
When to Seek Professional Guidance
While occasional hot and cold sensations are normal physiological responses, certain signs indicate the need for medical evaluation. If these sensations become persistent, occurring without an obvious cause, or significantly interfere with daily life or sleep, consult a healthcare professional. For instance, unexplained weight loss, severe pain, or confusion accompanying temperature fluctuations warrant prompt medical attention.
Any sudden onset of severe hot or cold flashes, especially if unrelated to environmental changes or typical triggers, should also be discussed with a doctor. These “red flag” symptoms could point to an underlying condition that requires diagnosis and treatment. Seeking professional guidance ensures proper evaluation and management.