Extreme heat? Here’s why taking a cold shower isn’t the answer.

“An unexpected event that turns off enthusiasm”: thus defines the dictionary the expression “cold shower.”

Interestingly, even a  cold water shower  can bring us an unpleasant surprise. Immersing yourself in  ice water  to escape the heat of summer is almost a conditioned reflex on overwhelming hot days. However, what seems like a logical remedy can have the opposite effect, often making us feel worse. Professor Adam Taylor, a professor of Anatomy at the  University of Lancaster  (United Kingdom), shed light on this topic in a recent article published in The Conversation.

The Body’s Strategy for Heat Management

Our body is a  dynamic system  that consumes energy and disperses it as heat. It continuously produces energy, even while at rest, leading to a potential internal temperature rise of approximately  1 °C per hour . If this excess heat is not eliminated efficiently, our organs could face detrimental  damage . To prevent this, our body employs essential  cooling mechanisms  that can be likened to a radiator. The main cooling process is  convection , where excess heat is transferred to the environment through the skin, making the human body appear as a source of  infrared radiation  when observed with a thermographic camera.

Thermostat Regulation: How Our Brain Responds

When surrounding air heats up, our  natural thermostat  activates—the  Thermoregulator center , located in the preoptic zone of the hypothalamus. This prompts a cascade of physiological responses, such as the dilation of blood vessels beneath the skin and the initiation of  sweating , both crucial for dissipating heat. So, why would a  cold shower  (for instance, at about  15 °C ) hinder this process? While it may seem reasonable, exposure to cold induces a  vasoconstriction  effect. This narrowing of blood vessels limits blood flow to the skin’s surface, consequently reducing our body’s ability to shed heat effectively.

Paradox of Cold Showers: The Hidden Dangers

This interaction yields a paradox: rather than shedding heat,  warmth is trapped  within the body. The sensory deception follows; after a cold shower, we may feel a momentary sensation of freshness as our skin receptors sense the low water temperature. Yet, on a systemic level, thermoregulation becomes  disrupted . “Ultimately, in a cold environment, the human body aims to retain heat, not to expel it,” says Taylor. Additionally, the sudden change from warm to cold water can trigger a rapid  increase in blood pressure . The heart must exert more effort to circulate blood through suddenly constricted peripheral vessels—a matter that should not be taken lightly by those with  hypertension  or cardiovascular issues.

Hygiene Considerations: The Importance of Temperature

Lastly, hygiene plays a crucial role in this discussion. Some dermatologists argue that  cold water  is less effective at eliminating  sebum  (body oil). “The best practice is to take a bath or shower with warm water, around  26-27 °C ,” suggests Taylor. At this temperature, our body can efficiently bring blood to the surface to cool down without triggering energy-consuming defense mechanisms. Should we wish to lower our body temperature further, it’s better to do so gradually by immersing one part of the body at a time. As is often the case in medicine, a  moderate approach  proves to be the most effective.