Postural Orthostatic Tachycardia Syndrome (POTS) is a disorder of the autonomic nervous system (ANS), the body’s involuntary control center. This malfunction, known as dysautonomia, affects many systems, including circulation, digestion, and heart rate. Individuals with POTS frequently experience an array of symptoms when moving from lying down to standing up, most notably a significant increase in heart rate. This underlying autonomic dysfunction often compromises the body’s ability to maintain a steady internal temperature.
The Autonomic Nervous System and Temperature Control
The autonomic nervous system (ANS) functions as the body’s primary thermostat, keeping the core temperature within a narrow, healthy range. The ANS controls involuntary functions, including breathing, heart rate, and complex temperature regulation. The hypothalamus, a small region in the brain, acts as the central control unit, receiving input from temperature sensors throughout the body.
When the body needs to cool down, the ANS triggers processes like sweating, which uses evaporation to dissipate heat from the skin’s surface. It also signals blood vessels near the skin to widen, a process called vasodilation, increasing blood flow to the surface to release heat. Conversely, when the body is cold, the ANS initiates vasoconstriction, narrowing blood vessels to reduce blood flow to the skin and conserve warmth at the core.
POTS and the Disruption of Thermoregulation
POTS is characterized by a malfunction in ANS signaling, which directly interferes with the body’s ability to coordinate temperature responses. The core feature of POTS is a failure in vasoconstriction, especially in the lower body, leading to excessive blood pooling in the legs upon standing. This failure in blood flow regulation also affects the temperature control mechanisms that rely on blood vessel changes.
The brain’s central thermoregulatory centers may receive confused or delayed signals, causing the body to react inappropriately. For instance, attempting to cool the core may trigger vasodilation, but this can exacerbate blood pooling and reduce circulating blood volume. The resulting cardiovascular strain often forces the heart rate to climb dramatically, which is the defining characteristic of POTS and can worsen symptoms like lightheadedness and fatigue. This dysregulation means the internal thermostat operates with a wider tolerance, failing to initiate responses until the core temperature has shifted significantly.
Specific Temperature Symptoms Experienced by POTS Patients
A frequently reported temperature-related issue is heat intolerance, where warm environments rapidly worsen the primary symptoms of POTS. Heat causes blood vessels to dilate, increasing blood pooling in the lower extremities and severely reducing the volume of blood returning to the heart and brain. This forces a compensatory increase in heart rate, making standing, exercising, or being in a hot shower challenging.
Conversely, many patients experience profound cold sensitivity, especially in the hands and feet. This manifestation is often the result of inappropriate or exaggerated vasoconstriction, which restricts blood flow excessively while attempting to conserve heat. The extremities may appear discolored, often reddish-purple, a condition known as acrocyanosis, and feel cold to the touch due to poor local circulation.
POTS can also lead to various sweating abnormalities, complicating the body’s natural cooling process. Some individuals experience hyperhidrosis (excessive sweating), even in cool conditions, while others may have anhidrosis (an inability to sweat properly). These erratic responses are evidence of disorganized signaling within the sympathetic nervous system, which controls vascular tone and sweat gland activity. Patients may also report rapid shifts in core temperature, moving quickly from feeling overheated to suddenly freezing, indicating a failure to maintain thermal stability.
Strategies for Managing Temperature Instability
Managing temperature instability in POTS focuses on reducing environmental stress and supporting compromised autonomic functions. Increasing fluid and electrolyte intake helps expand blood volume, making the circulatory system more resilient to temperature-induced changes. High-sodium fluids are particularly beneficial as they help the body retain the necessary plasma volume.
Layering clothing allows for continuous thermal adaptation, enabling the patient to quickly add or remove a garment in response to a sudden temperature shift. Cooling vests, neck wraps, and specialized personal fans can be powerful tools for managing heat intolerance by directly lowering the core or surface temperature. These devices provide external support to the body’s faulty cooling mechanisms, preventing symptoms from escalating.
Avoiding rapid changes in temperature is a practical step, such as transitioning slowly between an air-conditioned space and the outdoors, or lowering the temperature of showers and baths. Planning outdoor activities for cooler times of the day, like early morning or late evening, minimizes exposure to peak heat, thereby reducing the strain on the cardiovascular system. These proactive measures help stabilize the internal environment and reduce the frequency of symptom flare-ups.