Feeling sudden shifts between hot and cold can be a perplexing experience. The human body possesses an intricate system for maintaining a stable internal temperature, influenced by a variety of internal and external factors.
How Your Body Regulates Temperature
The body’s ability to maintain a consistent internal temperature, typically around 98.6°F (37°C), is called thermoregulation. This process is orchestrated by the hypothalamus, a small region in the brain that acts like a thermostat. The hypothalamus constantly monitors the body’s core temperature, receiving input from temperature receptors throughout the skin and internal organs.
When the hypothalamus detects a deviation from the ideal temperature, it initiates responses to either generate or dissipate heat. If the body is too warm, it signals sweat glands to produce sweat, which cools the skin as it evaporates. Blood vessels near the skin’s surface also widen (vasodilation) to increase blood flow to the skin and release heat into the environment. Conversely, if the body is too cold, the hypothalamus triggers shivering, involving rapid muscle contractions to generate heat. Blood vessels constrict (vasoconstrict) to reduce blood flow to the skin and conserve heat within the core.
Everyday Reasons for Temperature Fluctuations
Many common daily experiences can lead to feelings of being hot then cold. Environmental changes are a frequent cause; moving from a warm outdoor setting to an air-conditioned room can trigger the body’s natural cooling mechanisms, sometimes leading to a chill. Similarly, a draft in a room can cause localized cooling, prompting a body reaction.
Stress and anxiety can also induce temperature shifts. When experiencing stress, the body activates its “fight-or-flight” response, causing a rapid increase in heart rate and blood flow to muscles. This physiological arousal can lead to sudden warmth, followed by sweating as the body attempts to cool down, potentially resulting in a chill.
Minor illnesses, such as colds or the flu, frequently involve fevers and chills. A fever is the body’s natural response to infection, where the hypothalamus raises the body’s temperature set point to create an environment less favorable for pathogens. As the body works to reach this higher temperature, it can experience chills and shivering. Once the fever breaks, the body actively cools itself through sweating, which can then lead to feeling cold.
Physical activity also impacts body temperature. During exercise, muscles generate heat, raising core body temperature. The body responds by increasing sweating and vasodilation to dissipate this heat. After intense exercise, especially if in a cool environment, the rapid cooling from sweat evaporation can cause a sensation of cold. Certain foods can influence body temperature; spicy foods, for instance, contain capsaicin that can trigger sweating, leading to a cooling sensation. High-protein or fatty foods require more energy to digest, which can temporarily increase body heat.
Medical Conditions and Hormonal Influences
Beyond everyday occurrences, medical conditions and hormonal changes can significantly affect the body’s temperature regulation, leading to alternating hot and cold sensations. Hormonal shifts are a prominent factor, particularly during menopause. Hot flashes and night sweats are common symptoms experienced by women during perimenopause and menopause, characterized by sudden intense warmth, flushing, and profuse sweating. These episodes occur when fluctuating estrogen levels impact the hypothalamus, causing it to misinterpret slight changes in core body temperature and initiate an exaggerated cooling response. The subsequent rapid heat loss through sweating can then result in a chill.
Thyroid disorders also play a role in temperature sensitivity. The thyroid gland produces hormones that regulate metabolism, which directly influences heat production. An overactive thyroid (hyperthyroidism) accelerates metabolism, causing individuals to feel warmer than usual and experience increased sweating and heat intolerance. Conversely, an underactive thyroid (hypothyroidism) slows metabolism, leading to reduced heat generation and a heightened sensitivity to cold.
Anemia, characterized by a low red blood cell count or insufficient hemoglobin, can impair the body’s ability to transport oxygen and heat efficiently. This can result in individuals feeling persistently cold, especially in their extremities, as their bodies struggle to generate and distribute warmth. Low blood sugar (hypoglycemia) can also trigger a stress response, releasing hormones that can cause sweating, shakiness, and warmth, potentially followed by chills as blood sugar levels stabilize. Some medications may also have side effects that interfere with thermoregulation, leading to temperature fluctuations.
When to Seek Professional Medical Advice
While occasional temperature fluctuations are often benign, there are instances when seeking professional medical advice is advisable. If hot and cold sensations are persistent, severe, or significantly disrupt daily life, consult a doctor. This includes situations where these fluctuations are accompanied by unexplained weight loss, severe pain, dizziness, or unusual fatigue.
For fevers, medical attention is warranted if an adult’s temperature reaches 103°F (39.4°C) or higher, or if a fever lasts longer than three days. For infants under three months, a fever of 100.4°F (38°C) or higher requires a doctor’s visit. For those aged three to six months, seek medical advice for a fever of 102°F (38.9°C) or higher. Additional symptoms like a rash, stiff neck, confusion, persistent vomiting, difficulty breathing, or seizures alongside temperature changes also necessitate immediate medical evaluation. This information is for general knowledge and does not replace a medical diagnosis.