Although hyperthermia has been out of favour for years (see Special Report, pages 6-9), pioneering scientists are now experimenting with thermal therapy using infrared energy-a non-visible band in the electromagnetic (EM) spectrum. This EM band lies just below visible red light-hence 'infrared', or 'below the red'-with three wavelengths: near; middle; and far infrared (FIR), the longest waves of the three.
Although FIR wavelengths are too long for us to see, we experience this naturally occurring energy from the sun (and even a hot lightbulb) as a gentle radiant heat, warming us by direct light conversion without raising the temperature of the surrounding air. This eventually induces an increase in body temperature by causing bodily fluids to move around more quickly (Int J Biometeorol, 1989; 33: 145-50), leading to profuse sweating, but at a much lower temperature than with ordinary thermal heat such as that produced by, say, a Finnish sauna.
Much of the research on thermal effects comes from the Far East, including studies at Kagoshima University in Japan. In fact, the researchers' early studies into the use of FIR saunas for patients with chronic heart failure (CHF) showed that saunas can help to improve the function of the lining of blood vessels and their ability to dilate, suggesting a therapeutic role in atherosclerosis (J Am Coll Cardiol, 2002; 39: 754-9).
In the study, 20 patients-average age 62 years-with moderate or severe CHF, were given 15-minute daily saunas followed by bed rest and compared with a set of matched controls. Ultrasound was used to assess blood flow in all patients as reflected by dilatation of the coronary arteries, while cardiac function was determined by blood levels of a particular brain peptide, high levels of which are considered evidence of cardiac disease.
After just two weeks, 17 of the 20 patients using the FIR saunas saw significant improvements in blood flow and significant decreases in brain peptide compared with no changes among the controls.
Previously, the team had studied FIR sauna 'thermal treatment' in 25 younger men (average age 38 years) with at least one coronary risk factor such as diabetes, hypertension, high cholesterol or smoking. Although all initially had impaired vessel dilation, after just two weeks of daily FIR sauna treatments, their blood-vessel dilatation had significantly improved compared with 10 healthy controls(J Am Coll Cardiol, 2001; 38: 1083-8).
The Kagoshima findings have been replicated by a multicentre study of 188 patients that, again, showed improvements in cardiac function (J Cardiol, 2008; 52: 79-85), as well as by a US study from the Mayo Clinic (Circulation, 1995; 91: 2582-90).
Besides heart disease, FIR saunas can help chronic fatigue syndrome (CFS). In two patients with CFS, all symptoms-including fatigue, pain, sleep disturbances and low-grade fever-dramatically improved after 15-25 sessions of thermal therapy. Furthermore, the patients showed no signs of relapse a year later (J Psychosom Res, 2005; 58: 383-7).
FIR saunas can also successfully treat arrhythmias, peripheral heart disease, chronic pain and fibro-myalgia (Circ J, 2004; 68: 1146-51; J Am Coll Cardiol, 2007; 50: 2169-71; Psychother Psychosom, 2005; 74: 288-94; Intern Med, 2008; 47: 1473-6).
How does far infrared heal? In animals, the Japanese team found that sauna therapy increased protein levels of nitric oxide (NO) synthase in the aortic lining, the main blood vessel of the heart. Adequate levels of NO are essential for healthy heart function and coronary vessel dilatation. In their studies, after just one week, levelsof NO increased 40-fold and, even though that initial rise leveled off, its levels stayed 50-per-cent higher than before.
FIR saunas also lower levels of urinary prostaglandin, considered to be a marker of oxidative stress (Jpn Heart J, 2004; 45: 297-303).
Interestingly, tourmaline, a boro-silicate gemstone that naturally emits FIR waves, can significantly stimulate and enhance the activity of white blood cells and inhibit peroxidation of fatty acids (Int J Biometeorol, 1993; 37: 133-8). Other studies show that FIR promotes growth, enhances blood circulation in the skin and promotes restful sleep (Int J Biometeorol, 1989; 33: 145-50).
In addition, the Japanese team postulates that FIR saunas can even normalize weight, cholesterol and blood pressure, suggesting their use as a possible major preventative treatment for many of our modern-day lifestyle diseases (Exp Biol Med, 2003; 228: 1245-9).