Living in a part of the state where temperatures can plummet below freezing, most households have a drawer full of warm hats to offset the idea that ‘we lose most of our heat from our heads’. But do we really?
When recreating outdoors, from being comfortable for the activity-at-hand to potentially having to survive through an unexpected situation, body heat matters. Understanding the importance of core body and cerebral (head) temperatures just may change how to pack your backpack next time you venture out.
The temperature of a human body is largely dependent on the metabolic activity of the living tissue. Metabolic activity is just a fancy way to describe all the chemical reactions that occur in a living organism. These reactions are important for the production of energy, growth, and help to eliminate waste. Heat is a normal byproduct of many chemical reactions, therefore living bodies have a temperature, because temperature is how heat is measured.
When metabolism is increased (think hiking up the mountain chasing a chukar or digesting that second piece of pie), temperature increases. Our brains, because they do so much for us, have an incredibility high metabolic rate, and therefore a high blood supply. There is consistent and amazing temperature control of the brain occurring at all times to maintain optimum brain function, despite the variety of physiological conditions we put our brains through, from intense physical exercise (like going on an outdoor adventure) to sleeping. The human body, as a whole, is all about homeostasis, or maintaining a balance in the system for performance.
When going outside on a cool day, the most common body parts left uncovered by clothes or shoes are a person’s hands and head. While fingers are super important, the body has an effective way to shunt (slow) blood away from ‘non-essential’ tissues which helps to maintain the core temperature. However, such a mechanism is not in place for the head, because maintaining blood flow to the brain is critical for normal brain operation. Therefore, because our heads are generally the most exposed part of our bodies, it appears ‘we lose most of our heat from our heads’. If we walked outside with shorts on, a similar heat loss would occur through the exposed legs.
A study from the University of Manitoba in Canada revealed that when submerged in water without head coverings, the volunteers who were submerged in insulated clothes lost half as much heat as those who were only in swim suits. The majority of the heat lost was from the body in the water, there was no difference between the exposed heads. A head accounts for 7 - 9% of the body’s surface area, and results showed that only about 10% of heat loss was from the head, so it was proportional.
What does this mean for being prepared to be comfortable and safe outside during cold temperatures? Wear a hat, as well as other appropriate clothing! Your head is like the rest of your body parts, heat loss will occur if the heat is not trapped in. Having an extra layer or two on hand for all your different body parts is always a good idea. Get outside and explore, with all your clothes on, it’s good for humans everywhere.