People perceive heat through the sense of touch and temperature receptors located in the skin. The perception of heat is a result of how these receptors respond to the thermal energy of objects or the surrounding environment. The skin contains specialized nerve endings called temperature receptors or thermoreceptors, which are sensitive to changes in temperature. There are two primary types of thermoreceptors: cold receptors – also known as cold fibers, and warm receptors – also known as warm fibers. When an object or the environment is at a different temperature than our skin, it transfers thermal energy to our skin upon contact or exposure. The amount of thermal energy transferred depends on the temperature difference between the object and the skin. When thermal energy reaches the thermoreceptors, it triggers nerve signals to be sent to the brain through the nervous system. The brain receives these nerve signals and processes the information. Depending on the type of thermoreceptor activated (cold or warm), the brain interprets the signals as sensations of coldness or warmth. The perception of heat occurs when warm receptors are stimulated, indicating that the temperature is higher than the baseline temperature of the skin. In contrast, the perception of cold occurs when cold receptors are stimulated, indicating a lower temperature than the baseline of the skin. Human skin has a range of sensitivity to temperature, and it can detect temperature differences as small as 0.1°C (0.18°F). Temperatures outside the body comfort zone can be perceived as either hot or cold, depending on the direction of the temperature change. Heat perception can be subjective, and individual factors like age, gender, and past experiences can influence how someone perceives heat. Additionally, prolonged exposure to extreme temperatures can desensitize the thermoreceptors, leading to altered perceptions of heat and cold over time.
Heat perception is essential for several reasons and is a sort of survival mechanism that helps avoid potentially harmful situations and maintain equilibrium of the body. The human body needs to maintain a relatively stable internal temperature for optimal physiological functioning and this is called thermoregulation. When exposed to high temperatures, the body needs to recognize this increase in external heat and respond accordingly. Perception of heat prompts physiological responses, such as sweating and vasodilation (expansion of blood vessels) in the skin, which aid in cooling the body and preventing overheating. Heat perception serves as a warning system, helping individuals avoid contact with excessively hot objects or surfaces that could cause burns or injuries. This sense of heat prevents accidental harm by signaling that a surface, liquid, or environment is potentially dangerous due to its elevated temperature. The ability to perceive heat influences human behavior and allows people to adapt to their environment. For example, when it is hot outside, people are more likely to seek shade, wear lighter clothing, or consume cool drinks to maintain comfort and avoid heat-related illnesses. Heat perception enables individuals to assess their surroundings and make appropriate decisions. For instance, recognizing extreme heat can prompt people to take precautions during heatwaves or avoid venturing into areas with high temperatures, thus protecting their health and well-being. Heat perception also contributes to our ability to discern temperature differences. It helps us identify when something is warmer than our body temperature or when there are fluctuations in temperature, allowing us to adapt our behavior and clothing choices accordingly. Overall, the perception of heat is a vital aspect of human survival, helping us maintain homeostasis, avoid harm, and make informed decisions about our environment and activities in response to temperature changes.
Keeping cool during hot weather is essential to avoid heat-related illnesses and maintain comfort. Here are some effective ways to stay cool. Drink plenty of water throughout the day, even if you do not feel thirsty. Hydration helps regulate body temperature and prevents dehydration, which can worsen heat stress. Consume light and refreshing meals that do not require cooking, as using the stove or oven can add heat to your living space. Opt for lightweight, loose-fitting, and light-colored clothing. Light colors reflect sunlight, while loose-fitting clothes promote better airflow and allow sweat to evaporate more easily. If available, use fans or air conditioning to cool indoor spaces. Fans can help circulate air, and air conditioning provides significant relief from high temperatures. Taking cool showers or baths can help lower body temperature and provide immediate relief from the heat. Apply wet towels or damp clothing to your skin to create a cooling effect through evaporation. This is particularly effective when combined with a fan or sitting in a breezy area. Stay in shaded areas when outdoors, especially during the hottest parts of the day (usually midday). Shade provides relief from direct sunlight and can significantly reduce heat exposure. Minimize outdoor activities during the hottest parts of the day. If you need to be outside, try to schedule activities for the early morning or late afternoon when it is cooler. If possible, take advantage of swimming pools, lakes, or beaches to cool off. Water activities can be both fun and cooling during hot weather. If you are not used to hot weather, try to acclimate yourself gradually by spending short periods of time outdoors in the heat and gradually increasing the duration over several days. Keep an eye on weather forecasts and heat advisories. This will help you plan your activities and take necessary precautions during extreme heat events. Extreme heat can be dangerous, especially for vulnerable persons like the elderly, children, and individuals with certain medical conditions. If you or someone else shows signs of heat-related illness, such as heat exhaustion or heatstroke (e.g., dizziness, nausea, rapid heartbeat, confusion), seek immediate medical attention.
Hensel H. 1974. Thermoreceptors. Annu Rev Physiol. 36:233-49.
Miller VS, Bates GP. 2010. Hydration, hydration, hydration. Ann Occup Hyg. 54(2):134-6.
Mrowka R, Reuter S. 2016. Thermoregulation. Acta Physiol (Oxf). 217(1):3-5.
Tansey EA, Johnson CD. 2015. Recent advances in thermoregulation. Adv Physiol Educ. 39(3):139-48.