Sudden shifts from feeling overheated and sweaty to chilled and shivering can be confusing and uncomfortable. Understanding the biological processes that maintain our internal temperature, and factors that disrupt this balance, helps clarify why these shifts occur.
How Your Body Regulates Temperature
The human body maintains a remarkably stable internal temperature, typically around 98.6°F (37°C), through thermoregulation. The hypothalamus, a region in the brain, acts as the body’s central thermostat. It continuously monitors the body’s current temperature, comparing it to an ideal set point and initiating responses to restore balance.
If the body becomes too warm, the hypothalamus triggers cooling mechanisms to dissipate excess heat. This involves activating sweat glands, which release moisture onto the skin; as sweat evaporates, it draws heat away. Blood vessels near the skin’s surface also widen (vasodilation), increasing blood flow to release heat.
Conversely, when the body detects cold, warming mechanisms engage. Blood vessels constrict (vasoconstriction) to reduce heat loss, redirecting blood flow to vital organs. Shivering, rapid muscle contractions, generates heat through increased metabolic activity.
Common Triggers and Factors
Everyday circumstances often cause temporary temperature fluctuations. Moving quickly between environments with different temperatures, such such as stepping from a warm building into a cold outdoor space, can overwhelm the body’s immediate thermoregulatory adjustments. The body might briefly overshoot its cooling or warming response, leading to a sensation of being too hot or too cold.
Stress and anxiety can influence body temperature regulation. The “fight or flight” response, triggered by stress hormones like adrenaline, increases metabolic rate and alters blood flow, leading to a transient rise in core body temperature. Following this initial heating, the body’s cooling mechanisms may overcompensate, resulting in sudden chills and sweating. Certain dietary choices and hydration levels also play a role; consuming spicy foods can induce sweating, while inadequate fluid intake can impair the body’s ability to cool itself effectively.
Clothing choices can contribute to these shifts; wearing too many layers can lead to overheating and subsequent sweating, which then causes a chill once the clothing becomes damp or removed. Some medications, including certain decongestants, antidepressants, antipsychotics, beta-blockers, and diuretics, can interfere with the body’s thermoregulation processes. They may affect the hypothalamus, hinder sweating, or alter blood flow, making individuals more susceptible to temperature extremes.
Underlying Medical Conditions
Beyond common daily triggers, several medical conditions can disrupt the body’s ability to maintain a stable temperature, leading to hot and cold sensations. Hormonal fluctuations are a frequent cause, particularly in women. During perimenopause and menopause, declining estrogen levels directly affect the hypothalamus, causing it to become more sensitive to minor temperature changes. This often manifests as hot flashes, sudden waves of intense heat with sweating, frequently followed by chills as the body attempts to cool down. Hormonal shifts during the menstrual cycle, particularly before menstruation, can also trigger hot flashes or night sweats.
Thyroid disorders significantly impact metabolic rate and, consequently, body temperature. An overactive thyroid (hyperthyroidism) produces excessive hormones, accelerating metabolism and making individuals feel warm or sensitive to heat, often with increased sweating. Conversely, an underactive thyroid (hypothyroidism) results in insufficient hormone production, slowing metabolism and leading to cold intolerance and a persistent feeling of chilliness.
Infections and the fever response also involve temperature shifts. When the body fights an infection, it raises its temperature set point in the hypothalamus, triggering chills and shivering to generate heat and reach this new, higher temperature. Once the infection subsides and the fever breaks, the hypothalamus resets to the normal temperature, causing the body to release heat rapidly through sweating, which can lead to feeling cold.
Low blood sugar, or hypoglycemia, can also induce these symptoms. When blood glucose levels drop, the body releases stress hormones that can cause symptoms like sweating and rapid heart rate. The body’s response to low glucose can also include peripheral vasodilation and suppression of shivering, which leads to heat loss and a sensation of coldness. Damage to the autonomic nervous system, a condition called autonomic neuropathy, can impair the nerves responsible for involuntary functions like sweating and blood vessel control. This nerve damage can prevent the body from effectively regulating its temperature, resulting in difficulties with heat dissipation or conservation, and fluctuating sensations of hot and cold.
When to Consult a Doctor
While temporary temperature fluctuations are often harmless, certain indicators suggest a need for medical evaluation. If these shifts become persistent, worsen over time, or significantly interfere with daily activities, seeking professional advice is recommended.
Consult a doctor if sweating and freezing episodes are accompanied by other concerning symptoms. These might include unexplained weight changes, persistent fatigue, prolonged or recurrent fevers, or dizziness. A sudden onset of these symptoms without an apparent trigger, or if there is concern about potential medication side effects, warrants medical attention. A healthcare provider can diagnose the underlying cause and recommend appropriate management strategies.