Why We Get Colder As We Age — The Betrayal Of Our Immune System

Keeping warm and staying comfortable gets harder the older we get.

While your ambient body temperature may not be something you regularly think about, thermoregulation (the ability to maintain a comfortable body temperature) is an incredibly complex and important process. Thermoregulation is essential for sustaining life and upkeeping our internal core temperatures, and it must be achieved no matter what your surrounding environment is — such as where you live or what season you may be experiencing.

Interestingly, the process of staying warm is energy-intensive (especially during the colder winter months), and therefore some people are more likely to struggle when it comes to maintaining their baseline core temperature. This is particularly apparent in older populations. Research shows that it becomes significantly more challenging to keep warm as you age. 

Poor thermoregulation can lead to some serious issues, ranging in severity from discomfort and mild mood changes to the slowing down of the heart rate and breathing. These symptoms can be life-threatening if you experience a dangerous drop in your internal core temperature.

So, why are older people at greater risk of poor thermoregulation? While this may seem an inevitable fact of aging, researchers are working to better understand the true physiological reason for impaired thermoregulation in seniors.

More research is still needed to get to the bottom of this issue, but new findings suggest that natural changes in our aging immune system may be partially to blame.

Understanding thermoregulation

To better understand how age affects temperature regulation, we first must understand how our body is able to change and adapt our temperature based on our surroundings. 

At a baseline level, the body is always striving to keep the internal core temperature between 36.5–38.5 ℃ (97.7–101.3 °F). However, depending on where you live, it is highly unlikely that your external environment will always meet this exact temperature range. Therefore, the human body has developed ways to conserve or release heat to prevent straying too far from the ideal internal temperature range.

Examples of the body’s responses to external temperatures include:

Responses to heat

• Increased sweating: Cools the surface of the skin

• Vasodilation (expansion of the blood vessels): Allows for increased evaporation of heat

• Decrease in metabolism: Helps to burn less energy and produce less internal heat

Responses to cold

• Thermogenesis (shivering): Helps to produce extra heat in muscles subjected to cold temperatures

• Vasoconstriction: Causes blood vessels to shrink, which can help prevent heat loss

• Increase in metabolism: Burns more energy and produces more internal heat

When these processes are working correctly, our bodies can quickly adjust our internal temperature depending on our external environment. However, when these processes become impaired or more difficult, we can experience periods of increased warmth or coldness — both of which can become problematic if not adequately addressed.

Why we get colder as we get older

If thermoregulation is so important to maintaining adequate health and function, why does it become harder to achieve as we age?

Research into age-related thermoregulation problems has provided a variety of possible causes for this condition. While it was previously thought to be caused by changes to the walls of our blood vessels, impairing the speed in which blood studies our extremities, new research has found a connection between age-related fat loss and our immune system.

Subcutaneous fat, the bottom layer of our skin, is essential for providing the protection, support, and temperature control we need to keep warm. When we age, it is normal for our subcutaneous fat layer to thin, leaving our bones and organs with less padding and insulation.¹

This decrease in fat padding was previously believed to be one of the primary reasons for age-related heat loss, but it may be more closely linked to the immune system cells that are lost when these fat cells disappear.

A 2021 study discovered that we store essential protective immune system cells in our fat.² During the study, it was found that aging mice lost innate lymphoid cells (ILC2) due to their natural age-related fat loss.​​ The ILC2 cell’s primary role is to restore and rebuild body heat during cooler periods, so any loss of these cells could explain age-related thermoregulation issues.

Interestingly, when the researchers attempted to stimulate the production of new ILC2 cells in aging mice, the mice were more likely to experience poor thermoregulation when exposed to the cold. But, when already existing ILC2 cells were transplanted from a younger mouse to an older one, they were found to be more resistant to colder temperatures.

While more research is needed to fully understand the impact of our immune system on internal temperature control, it is clear that age-related changes pose many challenges for certain systems in our body that are required for thermoregulation.

Other reasons why we become more sensitive to cold

Besides aging, other factors can contribute to increased cold sensitivity over time. If you or someone you love has recently been struggling to stay warm, we recommend speaking with your primary care provider, as it could be a sign of other health issues that may require treatment.

Other medical reasons why people can experience increased sensitivity to cold include:

Cardiovascular disease

Blood circulation plays a major role in transferring heat throughout our bodies. When blood flow is restricted to any areas of the body (often our furthest extremities like feet, lower legs, and hands), they can quickly start to feel cold.

Cardiac conditions like peripheral artery disease (PAD), congestive heart failure (CHF), and coronary artery disease (CAD) can cause blood flow disruptions. This is a key reason why you should speak to your doctor if you are noticing increased cold sensitivity.³

Anemia

Occurring as the result of too few healthy red blood cells, people with anemia struggle to carry enough oxygen to their organs. When this occurs, feeling cold and tired is quite common.⁴

Getting adequate treatment for anemia (including iron supplementation) is essential for reducing these symptoms and promoting improved thermoregulation.

Kidney disease

As essential organs responsible for filtering out waste and excess water from our bodies, kidneys play an essential role in temperature regulation. When our kidneys are not functioning well, waste and fluid build up in our body, which in turn reduces our internal body temperature and makes us more susceptible to the cold.

Diabetes

Uncontrolled diabetes can cause damage to many organs in the body and have a profound impact on your ability to thermoregulate. From numbness and poor circulation caused by diabetic neuropathy to the increased risk of developing kidney disease, it is highly recommended that people with diabetes pay close attention to their treatment plan to reduce the risk of cold sensitivity and other complications.

Thyroid issues

As the driving force behind our metabolism, our thyroid is a key player in maintaining thermoregulation. For those diagnosed with hypothyroidism (low function and production of thyroid hormones), cold sensitivity is a common side effect.

To prevent excessive cold sensitivity, people with this condition should speak to their doctor about available treatment options.

Medication side effects

Some medications used to treat these conditions can also cause you to feel cold! Medications like beta-blockers (used to slow a person’s heart rate) and Synthroid (used to treat hypothyroidism) can increase cold sensitivity.⁵

If you are noticing a change in your ability to stay warm after taking a new medication, speak with your healthcare provider about other possible options to better treat your needs.

Don’t ignore the cold

Combining one or any of the above conditions with aging creates the perfect storm for developing serious complications of poor thermoregulation. Because we've come to accept that older adults are naturally cold, they may be less likely to seek care for this condition. This, in turn, can lead to hypothermia.

Defined as a core body temperature below 35℃ (95°F), hypothermia can develop quickly and is capable of causing significant health complications. While most people associate hypothermia with wintery conditions, seniors can develop symptoms of hypothermia in rooms with temperatures between 20–25℃ (68–77°F).

As a reminder, you should seek medical attention if you have started to feel cold sensitivity symptoms that are:

• Newly onset

• Getting progressively worse

• Difficult to manage even when you are in adequately warm spaces

• Interfering with your day-to-day activities

Signs and symptoms of hypothermia

Just like any other potential health risk, knowing how to identify the early signs of hypothermia is one of the best ways to keep you and your loved ones safe.

Some examples of early signs of hypothermia include:

• Cold feet, hands, and other extremities

• Puffy or swollen face

• Shivering (though this is not observed in all patients with hypothermia)

• Pale, cool skin

• Slow or slurred speech

• Fatigue, weakness, and appearing very sleepy

• Becoming suddenly angry, confused, or disoriented

Unfortunately, if these early symptoms are not picked up on, a person can develop more severe symptoms that can become life-threatening.

Examples of late-stage hypothermia symptoms include:

• Difficulty moving and increased clumsiness

• Stiffness and rigidity to the arms and legs

• Slow heartbeat

• Shallow and slow breathing

• Loss of consciousness and potential death

If you are with someone who you believe may be suffering from hypothermia, be sure to contact emergency services right away. If possible, move them to a warmer location, use warm blankets and towels, and stay with them until emergency responders have arrived. Do not place the person in a warm bath or offer them a heating pad — the sharp temperature change can be damaging to their body and will be very painful.

Tips for keeping warm with age

While our bodies may require extra assistance keeping warm as we age, finding ways to support your core body temperature is an essential skill to learn as early as possible. No matter where you live or how old you are, here are some of our top tips for keeping warm at any time of year:

• Keep your heater on: No matter how tempting it may be to turn off your heater to cut costs, keeping the heat at a regular temperature is a good way to ensure that your core body temperature doesn’t drop. Living in a consistently warm space will help your body regulate its temperature and will reduce the risk of developing hypothermia.

• Wear layers and pack extra layers on trips: Layers of clothing can provide insulation when you are feeling cold. If you are heading to a colder region, be sure to take extra layers, blankets, and jackets to ensure that you stay cozy and warm the entire trip.

• Maintain a healthy body weight: It is normal for older adults to lose fat over time. But, if this becomes excessive and the senior becomes underweight, it can be difficult for them to stay warm. Ensure that you are eating enough food to give your body fuel to create the energy and warmth you need.

• Seal your windows and doors: To prevent cold drafts from giving you a chill, close all windows and doors and ensure that they are adequately sealed and glazed, especially during winter months.

• Cover your feet and head: Covering your feet and head can be incredibly helpful in restoring heat to the body. Wearing warm fuzzy socks and a beanie with your outfit can help to prevent heat loss throughout the day.

The lowdown

As we age, we tend to feel the cold more. The latest research suggests that this is due to less subcutaneous fat, which can affect our immune system and have negative effects on our ability to maintain our body temperature.

If you have an existing medical condition or are on medication, these may also be affecting your body's ability to keep warm. Make sure you consult your healthcare provider to see if there is anything that can be done to support your body's thermoregulation.

To prevent complications arising from your heightened sensitivity to the cold as you age, take measures to keep warm and watch out for symptoms of hypothermia. Consult your doctor if you have any new symptoms or concerns.

Souces:

1. Aging changes in skin | Medline Plus

2. IL-33 causes thermogenic failure in aging by expanding dysfunctional adipose ILC2 (2021)

3. Feeling colder as you get older? Here are some reasons why | Providence

4. Anemia | Cleveland Clinic

5. Why am I always cold? | GoodRx Health

Other sources:

• What is thermoregulation, and how does it work? (2021)

Claire Bonneau is a medical writer and certified trauma operating room nurse.