Why Do People Shiver When They Feel Cold?

Shivering is a common bodily reaction that occurs when we feel cold, but have you ever wondered why this happens? Shivering is more than just an involuntary response to low temperatures; it is a biological mechanism designed to help the body maintain its core temperature. When we feel cold, the body triggers a series of reactions, one of which is muscle contractions or shivering, to generate heat and prevent the body’s temperature from dropping to dangerous levels.

In this article, we’ll explore why people shiver when they feel cold, how this process works, and what it tells us about the body’s ability to regulate temperature. We’ll also look into other possible causes of shivering and how it relates to overall health and well-being.

What Is Shivering?

Shivering is an involuntary bodily function characterized by rapid, repetitive muscle contractions that generate heat. It typically occurs when a person is exposed to cold temperatures or in response to a sudden drop in body temperature. Shivering is part of the body’s natural thermoregulation process, which helps maintain a stable core temperature of approximately 37°C (98.6°F).

Shivering is the body’s way of producing heat through muscle activity. When the muscles contract and relax rapidly, it generates friction and energy in the form of heat, helping to warm the body. In some cases, people may also experience shivering in response to fever, stress, or other factors that affect the body’s temperature regulation system.

Why Do People Shiver When They Feel Cold?

The main reason people shiver when they feel cold is to generate heat and maintain their core body temperature. Our bodies are equipped with a sophisticated temperature regulation system that constantly monitors internal and external temperatures. When the body detects a drop in temperature, it initiates several mechanisms to prevent hypothermia, which occurs when body temperature falls below the normal range.

Here’s a closer look at why and how shivering happens:

1. Thermoregulation: The Body’s Temperature Control System

The human body has a built-in thermoregulatory system that keeps the core temperature within a narrow range to ensure proper physiological function. This system is governed by the hypothalamus, a region of the brain that acts as the body’s thermostat. The hypothalamus constantly receives temperature signals from the skin and other parts of the body, allowing it to regulate heat production and heat loss.

When the hypothalamus detects a drop in external temperature or senses that the body’s core temperature is declining, it triggers various responses to preserve heat. One of the primary responses is shivering, which helps generate heat through muscle contractions.

2. How Shivering Works: Muscle Contractions to Generate Heat

When exposed to cold temperatures, the hypothalamus sends signals to the nervous system, instructing the muscles to begin rapid contractions. These contractions are involuntary and occur without conscious control. As the muscles contract and relax rapidly, they produce heat in the process. This heat helps to warm the blood and prevent the body’s internal temperature from falling too low.

The more the body shivers, the more heat is generated. This mechanism is particularly important in cold environments, where external temperatures can cause the body to lose heat quickly. Without shivering, the body’s temperature would drop, potentially leading to hypothermia and other serious health risks.

3. Shivering as a Survival Mechanism

Shivering is not just a response to feeling cold; it’s also a survival mechanism that helps protect the body from extreme temperatures. In very cold environments, shivering can make the difference between maintaining a safe body temperature and slipping into hypothermia. This is why you’ll often see people shivering when they’ve been exposed to cold weather for extended periods.

In extreme cold, the body prioritizes keeping the core (where vital organs like the heart and lungs are located) warm. Shivering helps maintain core temperature by generating heat that is circulated throughout the body, preventing the core temperature from falling to dangerous levels.

4. Energy Expenditure During Shivering

Shivering requires a significant amount of energy because it involves continuous muscle contractions. When the body starts to shiver, it taps into its energy reserves to fuel these contractions. This is why people may feel fatigued or tired after prolonged shivering in cold conditions. The body burns calories to produce heat, which is why you may also feel hungrier after being exposed to cold for an extended period.

While shivering is effective in generating heat, it is not a sustainable long-term solution for maintaining body temperature. Prolonged exposure to cold, even with shivering, can eventually deplete the body’s energy stores, leading to exhaustion and further heat loss.

Other Causes of Shivering

While shivering is most commonly associated with feeling cold, there are other causes of shivering that are not directly related to temperature. Shivering can be a response to fever, emotional stress, or even certain medical conditions. Here are some additional factors that may cause shivering:

1. Fever and Illness

Shivering often accompanies fever and illness. When the body is fighting an infection, it raises its internal temperature in an attempt to kill off harmful bacteria or viruses. This process is known as pyrexia, or fever. The hypothalamus resets the body’s temperature set point higher than normal, which can make a person feel cold even though their body temperature is rising.

Shivering is the body’s way of generating heat to match the hypothalamus’s new set point. Once the fever breaks, the hypothalamus lowers the set point back to normal, and the shivering subsides. This is a natural response to infections like the flu, pneumonia, or other bacterial or viral illnesses.

2. Emotional Responses: Anxiety or Fear

Shivering can also be triggered by strong emotions, particularly fear, anxiety, or stress. This type of shivering, sometimes referred to as nervous shivering, occurs because emotional stress can activate the body’s fight-or-flight response. When the sympathetic nervous system is activated in response to stress, it causes the muscles to tense up, leading to trembling or shivering.

In situations of extreme stress or fear, people may experience chills or shivering as their body prepares to react to a perceived threat. This reaction is part of the body’s survival instinct, similar to how the body reacts to cold by shivering to generate heat.

3. Post-Surgical Shivering

Many people experience shivering after undergoing surgery, a phenomenon known as post-anesthetic shivering. This occurs because anesthesia can interfere with the body’s natural ability to regulate temperature. As a result, body temperature may drop during surgery, leading to shivering as the body attempts to restore its normal temperature. Post-surgical shivering is generally harmless and typically resolves on its own once the body re-establishes its thermal equilibrium.

4. Hypoglycemia (Low Blood Sugar)

Hypoglycemia, or low blood sugar, can also cause shivering. When blood sugar levels drop too low, the body’s energy stores become depleted, and muscle function can become impaired. The nervous system reacts by sending signals to the muscles to contract and produce heat, which results in shivering. This can occur in people with diabetes who experience fluctuations in blood sugar levels or in those who haven’t eaten enough and have low glucose levels in their bloodstream.

In cases of hypoglycemia, consuming a source of sugar or carbohydrates can help raise blood sugar levels and alleviate the shivering.

5. Medications or Withdrawal Symptoms

Certain medications and substances can cause shivering as a side effect or during withdrawal. For example, medications like antidepressants, antipsychotics, and anesthetics may cause a temporary disruption in the body’s temperature regulation, leading to chills or shivering. Similarly, withdrawal from alcohol or drugs can result in tremors or shivering as the body readjusts to the absence of the substance.

In these cases, it’s important to consult a healthcare provider to determine whether the shivering is a side effect of medication or withdrawal and to receive appropriate treatment.

6. Thyroid Issues (Hypothyroidism)

Hypothyroidism, a condition in which the thyroid gland does not produce enough thyroid hormone, can also cause shivering or sensitivity to cold. The thyroid hormone plays a key role in regulating metabolism and body temperature. When levels of this hormone are too low, the body’s metabolic processes slow down, which can result in feeling cold and shivering more easily, even in mild conditions.

Treating hypothyroidism with thyroid hormone replacement therapy can help alleviate these symptoms.

How to Stop Shivering When Cold

If you find yourself shivering due to cold temperatures, there are several steps you can take to stop shivering and warm up your body:

1. Dress in Layers

Wearing multiple layers of clothing helps trap body heat and prevent further heat loss. Outer layers made of materials like wool, fleece, or down are particularly effective at insulating the body and keeping you warm in cold conditions.

2. Seek Shelter

If you’re outdoors and shivering, move to a warmer environment as soon as possible. Getting indoors or out of the wind will reduce the body’s exposure to cold temperatures, allowing you to warm up more quickly.

3. Drink Warm Beverages

Consuming warm beverages, such as tea, hot chocolate, or broth, can help raise your core body temperature and stop shivering. Avoid alcohol, as it can actually lower body temperature and increase the risk of hypothermia.

4. Exercise

If you’re in a situation where you can’t immediately access warmth, engaging in physical activity like walking, jogging, or jumping jacks can generate heat through muscle movement. Exercise helps raise your core temperature and reduce shivering.

5. Wrap Yourself in Blankets

If you’re indoors, use blankets to warm up your body. Blankets help retain heat and stop further heat loss, which will gradually stop the shivering.

When to Seek Medical Help for Shivering

While shivering is usually a normal response to cold temperatures or fever, it can sometimes indicate a more serious health issue. You should seek medical attention if you experience:

• Severe shivering that does not stop after warming up.
• Shivering accompanied by high fever (over 103°F) or symptoms of an infection.
• Shivering along with confusion, dizziness, or disorientation (which could indicate hypothermia or another serious condition).
• Persistent shivering along with symptoms of fatigue, weight gain, or constipation (which could indicate hypothyroidism).

In these cases, a healthcare provider can assess the cause of the shivering and recommend appropriate treatment.

Conclusion

Shivering is a natural and important response to cold temperatures, helping to generate heat and maintain the body’s core temperature. The process of shivering is controlled by the hypothalamus, which detects when the body’s temperature drops and signals the muscles to contract rapidly. While shivering is most commonly triggered by exposure to cold, it can also occur due to fever, emotional stress, or certain medical conditions like hypoglycemia or hypothyroidism.

Understanding why we shiver and how it helps the body stay warm can provide insight into the body’s temperature regulation system and its role in overall health. By taking appropriate steps to warm up when cold and addressing any underlying health issues that may cause shivering, individuals can maintain comfort and well-being in a variety of situations.