The sensation of feeling cold externally while simultaneously sweating, often called a cold sweat, is a common physiological paradox. This is not a malfunction but a complex response from the body’s temperature regulation system. The body’s priority is always to maintain a stable internal temperature, which sometimes requires activating both heating and cooling mechanisms simultaneously. Understanding this conflict requires examining how the body manages internal heat production against external cold exposure.
The Body’s Temperature Control System
The core of the body’s temperature regulation, or thermoregulation, is the hypothalamus, which acts as the central thermostat. This brain region constantly monitors the temperature of the blood, reflecting the internal core temperature. It also receives data on external temperature from thermoreceptors located in the skin.
When the core temperature rises above its set point (around 37°C or 98.6°F), the hypothalamus initiates heat-dissipating actions. Primary cooling responses include vasodilation, where skin blood vessels widen to allow heat to radiate away. Simultaneously, the sympathetic nervous system stimulates sweat glands to release moisture, which carries heat away as it evaporates.
Conversely, when the core temperature drops, the hypothalamus triggers mechanisms to conserve and generate heat. The first defense is vasoconstriction, which narrows skin blood vessels, shunting warm blood to the core organs to prevent heat loss. If this is insufficient, the body must actively produce more heat through metabolic processes, which is where the internal conflict often begins.
Sweating as a Byproduct of Metabolic Heat
The most direct reason for sweating when cold is the body’s aggressive effort to produce heat, known as thermogenesis. When the core temperature continues to fall despite conservation efforts, the hypothalamus activates systems that dramatically increase the metabolic rate. This survival mechanism is designed to quickly raise the internal temperature back to the set point.
Shivering and Non-Shivering Thermogenesis
One noticeable form of thermogenesis is shivering, involving rapid, involuntary skeletal muscle contractions. These movements convert chemical energy into kinetic energy, generating significant heat that can increase the body’s heat production by up to 500%. This intense internal activity causes the core temperature to rise sharply.
The body also uses non-shivering thermogenesis, primarily driven by brown adipose tissue (BAT), or brown fat. Brown fat is specialized to burn metabolic substrates to generate heat, unlike white fat which stores energy. This process is controlled by the sympathetic nervous system releasing norepinephrine to activate the brown fat.
The resulting flush of heat from both types of thermogenesis can be so immediate and substantial that it overshoots the immediate need. As the core temperature rises rapidly due to this internal heat generation, the cooling response is quickly activated as a countermeasure. This simultaneous heating and cooling triggers the sweat glands, even though the skin and surrounding environment still feel cold.
Other Factors Triggering Cold Sweats
Beyond the thermoregulatory conflict, several other biological and environmental factors can trigger the sensation of sweating while feeling cold.
Fever Break Cycle
One common scenario involves the body’s response to infection during the “chills and fever break” cycle. A fever occurs when the hypothalamus raises the core temperature set point, causing the person to feel intensely cold (chills) while the body works to reach that new, higher temperature. Once the immune system succeeds, the hypothalamus resets the set point back to normal.
To rapidly dissipate the excessive heat, the body initiates a massive cooling response, including profuse sweating known as the fever break. During this phase, the person sweats heavily but may still feel cold or clammy due to rapid surface cooling and wet skin.
Emotional Stress Response (Diaphoresis)
A separate mechanism involves the sympathetic nervous system’s emotional or stress response, termed diaphoresis. Anxiety, panic, fear, or intense pain trigger the “fight-or-flight” response, releasing adrenaline and other stress hormones. These hormones directly stimulate the eccrine sweat glands, particularly those on the palms, soles, and armpits, causing sweating regardless of core temperature.
Environmental Factors and Clothing
Environmental conditions and clothing choices also contribute to the cold sweat phenomenon. Wearing layers that are too warm or made of non-breathable materials, such as synthetic fabrics, traps the heat generated by normal metabolism. This trapped heat warms the core, triggering a mild sweat response. When the sweat evaporates under the clothing, it cools the skin, leading to a clammy sensation where the person is both sweating and feeling chilled.