Circulation: bringing more blood near the skin

As the body warms, blood vessels near the skin widen. More blood flows close to the surface, where heat can be released. You may notice this as a flush.

Blood also carries oxygen and nutrients to tissue and takes away substances produced through normal cell activity. The skin depends on that circulation for its daily maintenance. A Finnish sauna study, for example, measured a training effect in epidermal blood perfusion among regular sauna users.

The visible flush during a session is temporary. The larger point is that the skin is part of the body’s response to heat, and its blood supply changes as the body works to manage temperature.

Heat response inside skin cells

Cells respond to heat through a group of proteins called heat shock proteins. These proteins help cells manage temperature stress and maintain the function of other proteins.

In a study of normal human skin, researchers warmed skin to about 41°C for an hour and found increased levels of several heat shock proteins. The study involved five people and examined skin biopsies after heating. It gives us a direct look at a cellular response in human skin, not just a change in surface temperature. Read the study.

Sweating and the skin’s surface

Sweating is usually described as the body’s way to cool itself. It also contributes to the skin’s surface environment.

Sweat carries substances such as lactate and urea that are part of the skin’s natural moisturizing factor. It also carries dermcidin, an antimicrobial peptide that supports the skin’s surface defense.

Studies found lower hydration in skin areas that couldn’t sweat, and increased perspiration increased hydration. Another study found that sweating reduced the number of viable bacteria on the skin’s surface in healthy participants. These findings show how sweating connects temperature regulation with the skin’s moisture and protective functions. Read the skin-hydration study.  Read the study of sweat’s antimicrobial activity.

The lymphatic system is another part of the skin’s internal environment. It returns excess fluid from tissue to the circulation. Lymph movement depends on pressure changes and muscle activity, so it’s useful to distinguish lymph flow from sweating: sweat travels through glands to the skin’s surface, while lymph moves through vessels beneath the skin.

What research has found about sauna and skin

A controlled study compared 41 healthy adults who regularly used Finnish sauna with people who didn’t. Regular sauna users showed more stable skin-barrier function, greater water-holding capacity in the outer skin layer, and faster recovery after sauna exposure. The study examined Finnish sauna, not infrared, but it provides useful evidence about regular sauna use and skin physiology. Read the study.

Another study examined localized far-infrared treatment on facial skin. Twenty patients received treatments five days a week for six months. Patients and observers reported improvements in skin texture, roughness, and laxity. In laboratory tests, infrared-exposed dermal fibroblasts produced more collagen and elastin. The facial treatment was localized rather than a whole-body sauna, so it examined a different use of infrared. Read the study.

These studies examine different parts of the skin-health picture: barrier function during regular sauna use, the skin’s cellular response to heat, tissue warming beneath the surface, and visible changes reported after localized infrared treatment.

Changes I’ve noticed over time

After losing about 70 pounds, I had a significant amount of loose skin. I consulted a plastic surgeon, but the surgery would have cost $15,000. I didn’t want surgery, didn’t want to spend that much, and didn’t want to cut into my skin. The surgeon told me the stretched skin would never “come back” by itself. I accepted that.

I was already committed to two infrared sauna sessions a week for other reasons. I’d smoked for 35 years and drunk about a case of Diet Coke every day for 25 to 30 years. I believed regular sauna use would help mitigate the consequences of those habits.

Over the next three to six months, I noticed my skin was less loose and had some elasticity again. I’ve also seen tighter-looking skin in clients. One example is a man with visibly crepey skin whose skin looked tighter after 10 sessions. I’ve seen similar changes with other clients. My clients enjoy their sessions and return for many reasons, and many choose packages for regular use.

Skin health is a whole-skin response

The skin’s barrier, circulation, temperature regulation, moisture, and structural proteins all contribute to skin health. Infrared sauna engages several of these functions through warmth and the body’s response to it. Research has examined pieces of that response, while my own experience and what I’ve seen in clients give me another perspective on regular use.