What causes a decrease in temperature? Exploring Hypothermia and Other Factors

October 1, 2025 •

5 min read

According to a 2020 study, the average human body temperature has actually decreased over the last 200 years, suggesting that environmental and physiological factors may play a larger role than previously understood. This shift underscores the importance of understanding what causes a decrease in temperature in individuals and the various triggers, both external and internal, that can lead to a potentially dangerous drop.

Quick Summary

A decrease in body temperature is caused by excessive heat loss or insufficient heat production. Key factors include cold exposure, underlying conditions like hypothyroidism and sepsis, certain medications or alcohol use, and a person's age or mental state.

Key Points

Environmental Factors: Prolonged exposure to cold air, water, or windy conditions is the most direct cause of a decreased body temperature.
Underlying Medical Conditions: Diseases like hypothyroidism, diabetes, and sepsis can significantly impair the body's thermoregulation.
Medication and Substance Effects: Alcohol, sedatives, and certain antidepressants or blood pressure medications can interfere with heat production and retention.
Vulnerable Populations: Infants, older adults, and those with mental health or substance abuse issues are at higher risk due to compromised regulation and judgment.
Management is Critical: In cases of suspected hypothermia, immediate actions like removing wet clothing and gently rewarming are necessary, with severe cases requiring emergency medical attention.
Prevention is Key: Dressing in layers, staying dry, and limiting alcohol consumption in cold weather are effective strategies for prevention.

The human body is a finely tuned machine, constantly working to maintain a stable internal temperature, a process called thermoregulation. Normal body temperature typically ranges from 36.5 to 37.5 °C (97.7 to 99.5 °F), though a newer average has been observed. When heat loss surpasses heat production, core body temperature drops, leading to a condition known as hypothermia. While prolonged exposure to cold weather is the most common and widely recognized culprit, many other less obvious factors can contribute to a decreased temperature.

Environmental Causes of Decreased Temperature

Environmental exposure is the most straightforward cause of a significant drop in body temperature. The body can lose heat through several mechanisms, all of which are accelerated by cold, wet, or windy conditions.

Radiation: The body radiates heat as infrared electromagnetic waves to the surrounding air. When bare skin is exposed to cold air, this accounts for a large portion of total heat loss.
Conduction: Heat transfers through direct contact with a colder surface. Examples include sitting on cold ground or falling into cold water. Water conducts heat away from the body about 25 times faster than air, making immersion especially dangerous.
Convection: This involves the movement of air or water over the skin, carrying away the warm air or water layer near the body's surface. Wind, or the "wind chill factor," dramatically increases convective heat loss.
Evaporation: When sweat or water on the skin evaporates, it takes heat with it. While helpful in hot weather, having wet clothing in cold conditions leads to rapid heat loss.

Medical and Underlying Health Conditions

Beyond environmental factors, a person's health status can greatly influence their ability to regulate temperature. A number of medical issues can decrease heat production or impair the body's thermoregulatory response, resulting in a low body temperature.

Systemic Infections

A severe infection, such as pneumonia, can lead to sepsis, a life-threatening complication where the body's response to an infection damages its own tissues. While many people associate infection with fever, sepsis can cause a dangerously low body temperature, particularly in older adults or those with weakened immune systems.

Endocrine Disorders

These conditions affect hormone production, which plays a vital role in regulating metabolism and heat generation.

Hypothyroidism: An underactive thyroid gland reduces the body's metabolic rate, slowing down the processes that produce heat.
Hypoglycemia: Low blood sugar means the body lacks the fuel needed for energy production, which includes heat.
Hypoadrenalism and Hypopituitarism: These and other endocrine issues can interfere with heat-producing metabolic functions.

Neurological Conditions

The hypothalamus, located in the brain, is the body's primary thermostat. Conditions affecting the central nervous system can disrupt its function.

Stroke or Head Trauma: Damage to the hypothalamus from a stroke or injury can impair thermoregulation.
Neurodegenerative Disorders: Diseases such as Parkinson's and multiple sclerosis can affect the nervous signals that control temperature.
Spinal Cord Injury: Injuries to the spinal cord can interrupt the communication between the hypothalamus and the rest of the body.

Nutritional Deficiencies and Eating Disorders

Malnutrition: Without proper nutrition, the body lacks the energy reserves needed to generate heat.
Anorexia Nervosa: This eating disorder involves severe food restriction, leading to malnutrition and low body fat, which reduces insulation and heat production.

The Impact of Medications and Substances

Certain substances can interfere with the body's natural thermal regulation and response to cold, either by altering brain function or causing physiological changes like vasodilation.

Alcohol: Alcohol causes blood vessels to dilate, increasing blood flow to the skin's surface and accelerating heat loss, even as it creates a false sensation of warmth. It also impairs judgment, increasing the risk of staying in cold environments for too long.
Medications: Some drugs can lower body temperature as a side effect.
- Antidepressants: Certain types, such as Remeron and Elavil, can affect temperature regulation.
- Beta-blockers: These medications can blunt the body's response to cold.
- Antipsychotics, Sedatives, and Anesthetics: These can depress the central nervous system and interfere with the hypothalamic temperature control.
- Opioids: Pain medications like morphine and fentanyl can affect the body's ability to regulate its temperature.

Comparison of Decreased Temperature Causes


Cause Type	Examples	Mechanism	Key Treatment/Management
Environmental	Cold weather exposure, water immersion, wind, wet clothes	Excessive heat loss through radiation, conduction, convection, and evaporation	Remove from cold, remove wet clothes, provide warm blankets, rewarm gradually. Seek medical help for severe cases.
Medical Conditions	Hypothyroidism, Sepsis, Hypoglycemia, Neurological damage	Impaired heat production due to hormonal imbalances, metabolic issues, or disrupted thermoregulation signals from the hypothalamus	Treat the underlying medical condition; rewarming is part of supportive care.
Substance Use	Alcohol intoxication, recreational drug use, certain medications	Vasodilation, impaired judgment, and depressed central nervous system function, leading to accelerated heat loss	Stop substance use, rewarm the patient, and seek medical help for severe cases.
Age and Vulnerability	Infants, older adults	Less efficient temperature regulation and lower metabolic reserve	Monitor at-risk individuals during cold weather, ensure adequate heating and clothing.

Prevention and Management

Preventing a dangerous drop in body temperature often involves simple, common-sense measures, especially for those at higher risk. During cold weather, the acronym COLD can serve as a helpful guide.

Cover: Wear a hat, scarf, and mittens to prevent heat loss from your head, neck, and hands.
Overexertion: Avoid activities that cause excessive sweating, as wet clothing cools the body more quickly.
Layers: Wear loose-fitting, layered clothing. Wool or polypropylene layers are better at retaining heat than cotton.
Dry: Stay as dry as possible. Get out of wet clothes promptly.

If you suspect someone is experiencing hypothermia, take immediate action:

Gently move them out of the cold. If that is not possible, shield them from the wind and insulate them from the cold ground.
Remove any wet clothing.
Cover them in blankets, prioritizing the torso.
If conscious, offer warm (not hot) beverages.
Avoid direct heat, such as a hot bath, which can cause a rapid, dangerous shift in body temperature.
Call for emergency medical help immediately if their temperature is below 35°C (95°F) or if they show severe symptoms.

Risk Factors for Decreased Body Temperature

Certain individuals are more susceptible to dangerously low body temperatures.

Age: Infants and older adults have less effective temperature regulation.
Mental Health Conditions: Individuals with mental illness or dementia may not properly assess risk or dress appropriately for conditions.
Homelessness: People without adequate shelter are at a significantly higher risk of hypothermia from prolonged exposure.
Substance Abuse: Alcohol and drug use impair judgment and physiological responses to cold.
Underlying Illnesses: Chronic conditions such as diabetes, cardiovascular disease, and hypothyroidism increase susceptibility.
Fatigue: Exhaustion reduces the body's capacity to generate heat and tolerate cold.

For more detailed information on hypothermia, consult a trusted resource like the Mayo Clinic.

Conclusion

Understanding what causes a decrease in temperature is crucial for preventing and managing this potentially life-threatening condition. While cold environmental exposure is the primary culprit behind hypothermia, a range of internal factors—including medical conditions, medications, and substance use—can impair the body's ability to maintain a stable core temperature. Recognizing the risk factors and knowing how to respond is essential for protecting oneself and others from the dangers of low body temperature.

Frequently Asked Questions

Not necessarily. A slightly lower-than-normal temperature can be typical for some individuals, and the average human body temperature has been observed to be slightly lower than the long-held standard of 98.6°F. However, a consistently low temperature, especially below 95°F (35°C), could indicate an underlying issue and warrants medical evaluation.

Alcohol causes your blood vessels to dilate, or widen, which increases blood flow to the skin and accelerates heat loss from the body. It also impairs your body's natural shivering response and your judgment, making you less likely to seek warmth.

Yes. While fevers are a more common sign of infection, a serious infection can cause a drop in body temperature, a condition often associated with sepsis. This is particularly common in older adults, infants, and those with weakened immune systems.

Both infants and older adults have less effective thermoregulation. Infants have a high surface area-to-volume ratio and fewer heat reserves, while the elderly may have a slowed metabolism and less ability to sense cold.

Paradoxical undressing is a rare and dangerous phenomenon where a person with moderate or severe hypothermia becomes disoriented and removes their clothing, often due to a misguided feeling of warmth. This behavior increases heat loss and can worsen the condition.

Rewarming should be done gradually. The person should be removed from the cold, and any wet clothing should be replaced with dry garments. Warm blankets should be applied to the torso. Avoid rapid rewarming methods like hot water, which can cause shock.

You should seek immediate medical attention if a person's core body temperature is below 95°F (35°C) or if they exhibit symptoms like slurred speech, confusion, intense shivering, or loss of consciousness. Medical consultation is also advised for consistently low temperatures or for unexplained drops.