Understanding Hot Flashes: Is Your Head Actually Hot?

The hot flash is a phenomenon as disturbing as it is commonplace. For a moment, life goes on. The next moment, a wave of heat rises, spreads from the chest to the face, leaving behind reddened skin and beads of sweat. For many, this sudden heat is accompanied by an increased heart rate and a slight feeling of unease. Although brief – it usually lasts 30 seconds to five minutes – its intensity can be surprising and made worse by unpredictable timing.

[Article issu de The Conversation, écrit par Michelle Spear, Professor of Anatomy, University of Bristol]

A recent viral video has drawn attention to the intensity of the hot flash. The video shows a woman named Tracey Monique experiencing a hot flash at an outdoor event. In the video, his head is literally boiling.

The sight of wisps of steam rising from her head highlighted the dramatic effects of this common symptom of perimenopause. Often misunderstood or trivialized, the image of the hot flash draws attention to a phenomenon that affects approximately 75% of people in perimenopause.

The video has also sparked debate on social media, which reflects the complexity of hot flashes themselves. Some say the steam coming from Monique's head is because she took off her hat while out in the cold. But many women commented on the video saying it perfectly summed up what it feels like to have a hot flash.

Let's take a look at what really happens during a hot flash and why it can be so violent.

Hormonal instigators

At the heart of the hot flash is estrogen, hormones that play a vital role in regulating body temperature in women. Estrogen directly influences the hypothalamus, a small but essential brain structure often called the body's thermostat. The hypothalamus monitors and adjusts body temperature to maintain balance.

Under normal circumstances, the hypothalamus keeps the body within a narrow temperature range, adjusting blood flow and sweat production as needed. But during perimenopause, estrogen levels fluctuate unpredictably and eventually decline. These hormonal changes disrupt the ability of the hypothalamus to maintain the usual temperature.

Declining estrogen levels also make the hypothalamus overly sensitive to small changes in body temperature, misinterpreting them as signs of overheating. This triggers an exaggerated reaction aimed at cooling the body: a hot flash. This results in a sudden dilation of blood vessels, particularly in the skin of the upper body, to allow heat to radiate outwards. At the same time, the sweat glands are activated, which intensifies the feeling of heat.

Luteinizing hormone (also called LH, Editor’s note), which primarily regulates ovulation, also plays a secondary role in hot flashes. When estrogen levels decline, the pituitary gland (which regulates key hormones that control growth, reproduction, and metabolism) releases erratic spikes of luteinizing hormone. These spikes appear to increase the sensitivity of the hypothalamus, amplifying its misinterpretation of normal body temperature as overheating.

The cooling reaction

During a hot flash, the hypothalamus sends urgent signals to the autonomic nervous system which governs involuntary functions such as heart rate, blood pressure and sweating. This prompts the blood vessels near the skin to dilate – a process called vasodilation. This allows more blood to flow to the surface to release heat. This is why the face, neck, and chest may feel intense heat and appear visibly reddened during a hot flash.

Almost simultaneously, the hypothalamus activates the sweat glands of the upper body. The purpose of sweating is to cool the body through evaporation. In cold environments, this sweat can produce visible steam, as Monique's viral video shows.

But when the hypothalamus realizes that the body is not actually overheating, vasodilation decreases and the blood vessels return to their normal state. But the rapid cooling effect of sweat can leave women feeling chilled. This creates a roller coaster of sensations during and after the hot flash.

This sequence – heat, hot flash, sweat and cold – reflects the body's struggle to regain balance in response to a failing thermostat.

What is debated

While the feeling of heat is undeniable, whether hot flashes significantly increase skin temperature remains debated.

Thermographic studies, which use infrared imaging to measure heat patterns and surface temperature, have demonstrated measurable increases in skin temperature, particularly in the face, neck and chest.

But other research has found only minor or negligible changes in skin temperature. This raises questions about the direct correlation between heat perception and physiological changes.

Critics suggest that the feeling of heat comes more from impaired thermoregulation of the brain than from actual warming of the skin. Tools such as thermographic imaging may also fail to detect subtle or transient temperature changes. Or these changes may be masked by the evaporation of sweat.

It's also possible that changes in skin temperature, like other symptoms of perimenopause, vary greatly from person to person. Variability in estrogen levels contributes significantly – people who experience more irregular hormonal changes often report more intense or more frequent hot flashes. Factors such as genetics, lifestyle and environmental causes add to the diversity of experiences and intensity of symptoms.

Hot flashes are a complex interaction between hormonal, neurological and vascular responses. While the scientific debate over changes in skin temperature is unresolved, the lived experience of feeling hot and uncomfortable is undeniable. For many women, these symptoms are disturbing, even debilitating, and profoundly affect daily life.

Monique's viral video, featuring the striking image of steam rising from her head, resonated deeply with countless women – offering brutal visual proof of what they felt but they often found it difficult to express. Understanding the anatomy of a hot flash not only helps understand its mechanisms, but also highlights the importance of empathy and personalized approaches to managing this multifaceted symptom.