Your body needs to maintain a stable internal temperature within a set range to function optimally. This process is called thermoregulation.
Thermoregulation is a complex process, and many different factors can affect it. Your body knows how to adjust its temperature according to its environment.
What is thermoregulation?
Thermoregulation is your body’s ability to maintain a constant internal temperature despite external changes in temperature.
A 2023 article explains that thermoregulation is a homeostatic process that helps keep your body’s inner environment stable.
An optimal core body temperature is 98.6°F, but within a range of 97.7–99.5°F, functions involving your immune system, organs, and enzymes work optimally. Outside this range, you may experience symptoms of illness or a more extended period can also be life threatening.
What health conditions affect body temperature?
Many parts of your body help in thermoregulation, such as:
- brain
- skin
- muscles
- sweat glands
- nervous system, including nerves
- endocrine system, including glands
- circulatory system, including arteries and veins
Chronic health conditions affecting any of these organs and systems can also reduce your body’s ability to regulate temperature. Examples include:
- Nerve conditions: Conditions affecting small nerves can lead to difficulties with sweating and thermoregulation. For instance, conditions like Sjögren syndrome, an autoimmune condition affecting moisture-making glands, can make you sweat less.
- Spinal cord injuries: Spinal cord injuries, especially around the T6 vertebrae of your spine, traumatic brain injuries, and stroke can lead to difficulties with temperature regulation. This could be due to lost connections between your brain and the rest of your body.
- Brain and nervous system conditions: Conditions affecting the central nervous system, like multiple sclerosis and Parkinson’s disease, can affect how much you sweat and how your brain manages your body temperature.
- Hormonal conditions: Some hormonal conditions, like hyperthyroidism, can affect your metabolism and increase your body temperature.
- Peripheral nerve conditions: Conditions like diabetes can cause complications that make it more difficult for your body to manage sweating and regulate temperature.
About hyperthermia and hypothermia
The terms hyperthermia and hypothermia refer to excessively hot or cold core body temperature.
Hyperthermia
A 2022 article defines hyperthermia as having a body temperature higher than 104°F.
Possible causes include:
- sepsis and fever
- specific medications
- drug withdrawal
- hot weather
Not only can hyperthermia be uncomfortable, but it can also cause heat stroke, which can be life threatening. According to a 2023 article, heat stroke symptoms can include:
- low blood pressure
- fast heart rate
- excessive or no sweating
- fast, shallow breathing
- confusion
- lack of muscle regulation
- loss of consciousness
- seizures
- nausea and vomiting
- weakness
- hot, flushed skin
Hypothermia
Hypothermia is when your body loses heat faster than it can generate or absorb, reducing your body temperature. A 2024 article notes that symptoms generally occur below 95°F. They can worsen the colder you get.
The most common cause is prolonged exposure to cold surroundings, and rarely, overdosing on some medications can cause hypothermia.
Symptoms can include:
- shivering
- hunger
- nausea
- fatigue
- pale, dry skin
- high or low blood pressure
- fast, slow, or irregular heart rate
- fast breathing
- reduced judgment and memory
- lack of muscle regulation
- loss of consciousness
Extreme weather conditions
From scorching heat waves to freezing colds, extreme weather conditions can challenge your body’s ability to manage its temperature.
Extreme heat
A 2022 review notes that
Older adults (adults 65 years or older), people exercising or living outdoors, and people with cardiometabolic conditions like diabetes and heart disease may be more susceptible to side effects of higher temperatures, and increased air temperatures specifically can cause a higher number of deaths.
In the 1960s, the United States Global Change Research Program recorded two heatwaves each year in major U.S. cities, but this rose to six per year in the 2020s. With heat waves becoming more intense and frequent across the United States and beyond, conditions affecting body temperature regulation could grow over the next few years and decades.
Extreme cold
A 2019 article notes that excessive cold caused two-thirds of weather-related deaths in the United States between 2006 and 2010.
Of these deaths, more than half had links with alcohol consumption. Being an older adult and being outdoors for longer periods — for example, living outdoors or in a vehicle without heating poses a risk and can become life threatening.
Thermoregulation and infections
Infections can disrupt your body’s regular thermoregulation, and fever is a common symptom of infection.
A fever occurs when your brain’s hypothalamus (the part that regulates temperature, thirst, and more) tells your body to increase its core temperature.
A 1.8°F increase in body temperature increases your metabolism by at least 10%. In the short term, it causes effects like:
- enhanced immune function, which can mean higher white blood cell activity
- increased heart rate
- faster breathing
- increased use of fat and proteins for energy
- reduced growth of infectious agents like viruses
But if you have a high fever for a long time, then it can cause:
- brain damage
- irregular heartbeat
- increased inflammation
- water retention, or edema
- liver damage
- kidney damage
Doctors and healthcare professionals consider 104°F to be a high-grade fever. Seek immediate medical attention if your temperature reaches this level.
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