native american sweat lodge with sage smudge sticks

Native American Sweat Lodge

Sweat Lodges: A Medical View

Lawrence R. Berger, MD, MPH; and J. Eric Rounds, BS, MA, The Lovelace Clinic Foundation, Albuquerque, New Mexico
Introduction
Sweat lodges are becoming increasingly popular both within Native American communities and among nonIndians.1-3 In addition to their traditional use for purification of mind, body, and spirit, sweats are now frequently used as a component of substance abuse treatment and rehabilitation programs for incarcerated Native Americans. A resurgent interest in and respect for Native American culture and traditions among the general public, and the growing popularity of New Age spirituality, have also prompted a dramatic rise in the number of people participating in Native American sweat lodges.
There is great variation in how sweats are conducted. Some are led by recognized Native American spiritual leaders, take place over several hours with intense heat, and are restricted to persons with a profound commitment to tradition and ceremony. At the other extreme are sweats that are open to anyone, have no leaders, and are primarily social gatherings. While the spiritual and philosophical issues raised by the proliferation of sweat lodges are important, we focus in this article on the medical aspects. What are the potential health benefits of sweat lodges? What risk factors might prompt individuals to approach sweats with caution? What medical issues deserve further research? To help answer these questions, we conducted an extensive literature review. Relevant articles were identified via searches of Medline (1966-1997), Toxline (1966-1997), Science Citation Index (1966-1997), Sociological Abstracts (1963-1997), Biological Abstracts (1969-1997), Psychological Abstracts (1967-1997), and Carl (Un)Cover (1990-1997). We also searched the World Wide Web using the browsers “Infoseek” and “Excite.”
This article reviews the health risks and therapeutic benefits of sweating. Our goals are to stimulate research interest in the therapeutic value of sweat lodges, promote the health and safety of individuals considering participation in regular sweats, and highlight another aspect of traditional, Native American wisdom. We especially hope this information will be of value to health practitioners whose patients may ask for guidance regarding participation in sweats; and to sweat lodge leaders, who should consider the physical and medical condition of individuals, in addition to their emotional and spiritual preparedness, before inviting them to a sweat lodge.
This article is consistent with the IHS policy of encouraging “a climate of respect and acceptance in which an individual’s private, traditional beliefs become a part of the healing and harmonizing forces within his or her life.” By discussing the potentially beneficial medical and physical aspects of the sweat lodge, as well as the conditions that might warrant caution in its intensive use, we hope to increase the visibility of, and appreciation for, this powerful activity. In no way is our emphasis on physical health meant to diminish the profound spiritual and ceremonial importance of sweat lodges.
Potential Health Benefits
Natural health practitioners have recommended sweat therapy for persons with a variety of ailments, from infectious diseases to insomnia. There is growing scientific support fortheir enthusiasm based on laboratory work, clinical studies, and research involving heat chambers and saunas. Clinical studies of Scandinavian sauna-bathing are particularly relevant to sweat lodges. Both are often practiced weekly and involve high temperatures and high humidity generated by throwing water on hot stones, although saunas in the United States often use dry heat, as do some Native American sweat lodges.
Anti-infectious. The heat of a sweat lodge is capable of raising core body temperature, creating what might be called a “temporary fever.” In a sauna at 80 degrees Centigrade (C), adults raise their rectal temperature about 1 degree C after 30 minutes.7 There is increasing evidence that mild to moderate elevations of temperature can enhance specific and nonspecific immunity. Febrile temperatures have been shown to promote the migration of neutrophils, the production of antibacterial substances by leukocytes, and the antiviral activity of interferon. An experiment with mice infected with herpes virus provides a dramatic example of improved host defenses: increasing their core temperature by 2 degrees Centigrade improved their survival rate from 0% to 100%. Studies in humans have shown that children with chickenpox have a longer time to total crusting of lesions when treated with temperature-lowering doses of acetaminophen, and adults with rhinovirus have more nasal viral shedding when they receive aspirin rather than placebo.9
Human sweat contains immunoglobulin-A (IgA) and specific antibodies to such antigens as hepatitis B and tetanus. There are also many agents in sweat associated with the inflammatory response.17-21 These proteolytic enzymes, histamine, kinin, and interleukins very likely enhance resistance to viral, bacterial, and parasitic infections.They may provide local protection of the skin and prevent the invasion of harmful agents through the skin and into the bloodstream.
Certain infections, however, may actually be facilitated by increased body temperature. The best example is recurrent herpes simplex infections. So-called “fever blisters” are lesions caused by the recrudescence of latent herpesvirus infections. They occur during natural fevers or artificial elevations of body temperature.
Anti-cancer. Hyperthermia appears to be a promising modality for cancer treatment when combined with radiotherapy or chemotherapy, although the experimental body temperatures (41-45 degrees C) are well above those experienced in a sweat lodge. Yet there may also be anti-cancer benefits to raising body temperature to the febrile range. Elevated temperatures have been shown to retard the proliferation of certain tumor cells, increase the antitumor activity of interferon and interleukins, and enhance the killing efficiency of specific cytotoxic t-lymphocytes.
As in the case of infections, there is reason for caution in concluding that raised body temperature is uniformly helpful in cancer prevention and treatment. Laboratory studies indicate that hyperthermia can cause dysfunction of gene repair mechanisms and reduced natural killer activity of human mononuclear cells. Also, some animal studies have shown an increase in metastases following whole body heating.
Detoxification. The idea that deleterious “toxins” can be eliminated from the body by sweating is a popular one, as evidenced by these quotes from publications intended for the general public: “Sweating is one of our most important mechanisms of natural healing, since it allows the body to rid itself of unwanted materials”; “Impurities in many body organs are flushed out as the capillaries dilate and the heart increases its pace”; “‘Heat stress’…is very effective in releasing fat-stored toxins from the cells.” While there is no question that sweat glands are excretory organs, the clinical significance of human sweat as an excretory pathway for specific substances has received little scientific scrutiny. Human sweat is a dilute solution that contains mainly sodium, potassium, chloride, and bicarbonate.29 Urea, amino acids, glucose, magnesium, calcium, lactate, proteins, and enzymes also appear in sweat. The concentration of ammonia in sweat is 20 to 50 times higher than in plasma.30 Sweat appears to be an important excretory pathway for zinc and copper, and possibly other trace metals such as cadmium, manganese, aluminum, lead, iron, and nickel.31,32 Workers occupationally exposed to lead have extremely high levels of lead in sweat even when their blood lead levels are only moderately elevated.
Water-soluble bile pigments are excreted by the sweat glands of patients with severe liver disease. Patients with renal failure have elevated sweat potassium concentrations and increased sweating “may play a role in removal of sweat electrolytes from the body.”The concentration of urea in sweat is approximately the same as the plasma concentration. This accounts for the occurrence of “urea frost” on the skin of patients with uremia.
Street drugs (such as amphetamines, heroin, cocaine) and their metabolites are excreted in sweat, but usually in nanogram amounts. Medications, such as antineoplastic drugs, benzodiazepines, iodine, and antibiotics, are detectable in sweat. Ethyl alcohol is secreted in sweat in concentrations that approximate its concentration in blood.20
Healthy skin and treatment of skin disorders. Repeated sweat baths may promote healthier skin by several mechanisms including a direct therapeutic effect of heat, increased blood flow to the skin, and the delivery of substances within sweat itself. In a sweat lodge or sauna, the temperature of the skin can rise from 32 degrees C at room temperature to 40 degrees C or higher.42 Heat stress leads to an increase in cardiac output and vasodilation over the entire body surface.43 Blood circulation to the skin can reach up to 8 liters per minute in an adult (from less than one liter per minute at room temperature). As much as 50-70% of the cardiac output may be directed to the blood vessels of the skin (versus 5-10% at room temperature).
This dramatic increase in blood flow means increased perfusion and the delivery of oxygen, immune agents, and other substances to the skin. Wound healing may be accelerated by interleukins, chemokines, and nitrates in sweat that result in the generation of nitric oxide on the skin surface. Local hyperthermia and/or sauna bathing have been used to treat psoriasis, atopic eczema, warts, scleroderma, pemphigus, pityriasis versicolor, tinea, leg ulcers, fungal and atypical mycobacterial skin infections, and scabies. Sweat urea may function as a natural skin moisturizer.30 The excretion of medications via sweat can improve the treatment of resistant cutaneous fungal infections:
For example, orally administered griseofulvin and
ketoconazole are secreted into sweat, thereby quickly
reaching the stratum corneum where dermatophytes are
present, bypassing the slow diffusive pathway across the
epidermal cell layer… The best way to improve the
antifungal effect of these agents is to obtain maximal perspiration
while the patient is taking the drugs.
Other Conditions. A double-blind study of patients with perennial rhinitis found that raising intranasal temperature by inhalation of saturated hot air (42-44 degrees C) resulted in reduced rhinitis symptoms and increased nasal patency.51 Hot baths 1.5 hours before bedtime resulted in deeper and more restful sleep among a group of women aged 60-72 years with insomnia.
Pain relief and muscle relaxation from sweat baths may be of particular benefit in persons with musculoskeletal injuries, overuse ailments, arthritis and other rheumatic diseases, premenstrual syndrome, and insomnia.53-56 Heat may alleviate pain by releasing endogenous opioids and reducing anxiety.53,57 Heat may promote muscle relaxation by increasing the extensibility of collagen-rich tissues (such as tendons, fasciae, and articular capsules), increasing oxygen delivery to stressed muscles, speeding immune cellular repair, and reducing pain.47,53 The plasma concentration of prolactin increases during heat exposure.58 This physiologic effect, along with the relaxation induced by a sweat bath, might facilitate breast feeding.
Potential Health Risks
Injuries. Based on conversations with sweat lodge leaders, probably the most common hazards of sweat lodges are falls, lacerations, and abrasions from participants tripping or stepping on objects while walking barefoot to and from the lodge.
Acute musculoskeletal disorders. Laboratory studies suggest that higher temperatures can increase the breakdown of articular cartilage and tissues that contain collagen.55,59 In experimental animals, hyperthermia can exacerbate acute inflammation.53 These in vitro studies may explain why some patients with joint and musculoskeletal symptoms complain of increased pain after heat exposure. Several authors recommend that patients with acute inflammatory processes in muscles, joints, or back should not undergo heat stress in the first few days after injury, or while there is ache, swelling, redness, or tenderness at rest.
Pregnancy and women’s health. A prospective study of over 23,000 women found an increased risk of neural tube defects (spina bifida, anencephaly, or encephalocele) among infants born to women who were exposed to heat during the first trimester of pregnancy. The exposures were in the form of hot tubs, saunas, or fevers.61 This research supports animal studies concluding that heat is teratogenic.A review of pregnancy and the sauna in Finland concludes that “healthy pregnant women may safely have sauna baths throughout their pregnancy.”63 However, the review notes that the fetal heart rate rises during maternal hyperthermia and thermal stress may induce uterine contractions and lower uterine blood flow.63 Sweat iron loss coupled with a low dietary iron intake may result in a negative iron balance and anemia for women.64 At least one study found a lower sweat volume among females than males.65
Dehydration. A person who is dehydrated upon entering a sweat lodge is at risk of heat exhaustion, hypotension, and syncope. Dehydration lowers the sweating rate for a given core temperature, increases heart rate, and decreases cardiac output.
In very hot environments, water losses from sweating can approach two liters per hour.
Male infertility. In otherwise healthy men, increased scrotal temperatures are associated with decreases in sperm count and in the percentage of motile spermatozoa. These abnormalities are reversible when temperatures return to normal. Infertile men are advised to avoid hot environments.68,69 The contraceptive efficacy of a daily mild increase (1-2 degrees C) in testicular temperature during waking hours is under investigation.70
Cardiovascular conditions. Individuals with cardiovascular problems (such as hypotension or hypertension, congestive heart failure, or impaired coronary circulation), or who are taking medications which might affect blood pressure, need to exercise caution in exposing themselves to prolonged heat.71,72 During heat waves, chronic cardiovascular diseases are the most common underlying disorders among patients with heat stroke.73 Heat stress causes fluid shifts in the body as a result of both cutaneous vasodilation and fluid loss from sweating. Also, cardiac output increases in order to transfer internal heat to the outside environment via the skin and respiratory system.71,72 The rise in cardiac output (2.8 l/min for every one degree Centigrade increase in body temperature) is primarily due to changes in heart rate (which increases by about 30 beats per minute for each degree increase in internal temperature).43,44
Blood pressure usually falls during heat stress as a result of the redistribution of blood volume to skin and away from the splanchnic (gastrointestinal, splenic, and pancreatic), renal, and skeletal muscle circulations.43,44 Decreased coronary perfusion pressure, combined with increased blood viscosity (due to decreased intravascular fluid volume) and increased myocardial oxygen demand from tachycardia, all increase the risk of myocardial ischemia. Conversely, blood pressure may rise dramatically on exposure to cold, such as when a person leaves a sweat lodge on a winter’s day. Sudden cold exposure increases the work of the heart because of the very rapid transitory volume and pressure loads, accelerated heart rate, and increased sympathetic activity. These changes increase the risk of myocardial ischemia and arrhythmias.44,54,72 Changes in circulating blood volume, blood viscosity, and blood pressure also pose a risk for cerebrovascular events (syncope, stroke).
Children. When exposed to hot environments, children experience a much more rapid rise in core temperature than adults do. This is reflected in the excess death rate due to heat illness among infants and children during heat waves.Higher metabolic rates per unit mass, greater body surface area/mass ratio, and limited circulatory adaptation to increased cardiac demands play a role.7,66,74-76 Maturation of the ability to regulate body temperature by sweating is said to occur only at puberty.66,76 Children’s thinner skin layers (epidermis and dermis) also increase their susceptibility to burns,76a both from the hot steam and heated stones of a sweat lodge.
Medications. Sympathomimetic drugs may provoke tachycardia and arrhythmias with heat stress. Atropine, glutethimide, tricyclic antidepressants, phenothiazines, and antihistamines have anticholinergic action that can predispose to syncope and heat stroke.66,73 Diuretics can produce hypovolemia, hyperosmolality, and reduced evaporative water losses through a reduction in sweat rate.67 Barbiturates and beta-blockers can also impair heat loss mechanisms.77,78
The Elderly. The ability to maintain core temperature during heat stress decreases with increasing age because of decreased sweat gland function, cutaneous blood flow, and innervation to sweat glands.79,80 Also, elderly individuals may be prone to orthostatic hypotension and need to be cautious to avoid syncope when standing up after a sweat bath.72
Diabetes. The impact of sweat bathing on insulin levels is not easily predicted. Subcutaneously injected insulin is absorbed faster than usual in hot environments, probably because of increased cutaneous circulation. At the same time, heat exposure increases the secretion of catecholamines (such as noradrenaline) and possibly other insulin antagonists.54,58 Individuals with neuropathy can experience burns from lack of sensation and an impaired sweating ability.20,81
Alcohol abuse. Acute alcohol intoxication poses many hazards in the sweat lodge. Decreased judgement, balance, and coordination can lead to burns and falls. Both alcohol and heat stress dilate peripheral vasculature, increasing the risk of orthostatic hypotension and syncope; and both increase adrenergic activity, predisposing to cardiac arrhythmias.82 Chronic liver disease can lead to abnormal sweating because of autonomic dysfunction.83
Asthma. Smoke from cedar, sweetgrass, tobacco, or other plants used in sweat lodges may serve as pulmonary irritants. Humid air has a variable effect on patients with asthma, decreasing forced expiratory volume and airway conductance in some studies and increasing it in others.84-86 Bronchodilators in combination with heat stress may provoke tachycardia and arrhythmias.87
Skin disorders. The onset or exacerbation of certain skin disorders (eczema, cholinergic urticaria, acantholytic dermatosis, miliaria) have been linked to heat and sweating.42,88,89 “Heat rash” is caused by the plugging and rupture of sweat glands following sweating-induced skin maceration.77 Some skin disorders (e.g., psoriasis, miliaria rubra) can occlude sweat ducts, substantially reducing sweating.20 Sunburn decreases the responsiveness of the sweat gland and its capacity to deliver sweat to the skin surface.66
Kidney disease. Patients with chronic renal failure often complain of dry skin and pruritus, which may be due to the atrophy of sweat glands, elevated antidiuretic hormone, and a decreased sweating response.29,90 Excessive sweating may affect electrolyte balance, since patients with advanced renal failure have higher sweat concentrations of potassium.29
Neurologic disorders. Although some patients with multiple sclerosis (MS) show improvement after warming, about 80% suffer neurological deterioration (such as muscular weakness and ocular abnormalities) when subjected to heat. Until the early 1980s, the “hot bath test” was used in diagnosing the disease. The test was largely abandoned “because it sometimes resulted in permanent neurologic deficits in MS patients.”91 Patients with Parkinson’s disease can exhibit a range of sweating disorders.92
Patients with peripheral neuropathies (e.g., from diabetes, alcoholism, Guillain-Barre syndrome, leprosy) that impair sensation are obviously at risk for serious burns in the sweat lodge, both from hot steam and contact with the heated stones.
Other Conditions. Reduced ability to sweat can place a person at risk of heat stroke during a sweat lodge. Conditions associated with impaired sweating include extensive scarring from burns, total body electron beam irradiation, diabetes with neuropathy, Parkinsonism, multiple sclerosis, cervical spine lesions, central nervous system tumors, hypothyroidism, amyloidosis, injuries, or hemorrhages.29,92 Untreated hyperthyroidism can increase core heat production by up to 400%, greatly increasing the risks of heat exposure.73,78
Conclusions and Recommendations
The potential health benefits of regular participation in Native American sweat lodges are numerous. This is not at all surprising, given that sweat bathing has been practiced for thousands of years in many cultures throughout the world. What is very surprising is the scarcity of research about the practice, especially in light of the growing worldwide interest in complementary healing. Promising areas for research are the value of sweat bathing for preventing and treating infectious diseases (especially with the rise in antibiotic-resistant infections); treating arthritis (where heat can have paradoxical effects on inflammation); treating skin disorders (where remarkable increases in skin blood flow enhance both natural immunity and the delivery of medications); treating and reha72
THE IHS PROVIDER June 1998
bilitating individuals with alcohol and other substance abuse disorders (for example, there are no studies estimating the amounts of drug metabolites excreted during profuse and prolonged sweating); and preventing cancers, their metastases, and post-treatment relapses. Research is especially urgent where current evidence is conflicting, such as the impact of elevated temperatures on tumor behavior, the immune system, and joint disorders.
The sacred and ceremonial nature of traditional sweat lodges does not mean their physical effects cannot be evaluated. For example, the value of sweat lodges as an adjunct to alcohol treatment programs could be assessed by comparisons among treatment sites, perhaps with a crossover design. Furthermore, disregarding spiritual aspects, the sweat lodge and the sauna are remarkably similar physically, and possibly have an identical origin.93 Conditions of heat and humidity in the sweat lodge can be duplicated in the sauna, making possible randomized trials of individuals with specific medical conditions. Any research involving sweat lodges per se (as opposed to studies of sweating in clinical or laboratory settings) must necessarily involve a collaboration among participants, traditional healers, and investigators. What factors, if any, do traditional healers or Tribes think are important to study? How might studies be undertaken with full respect for traditional values and practices? How would results be shared? The ethical and cultural implications of such research are as important to consider as the cultural issues.
The potential health hazards of sweat lodges need not exclude individuals with mild or moderate risk factors from participation. The social, spiritual, and psychological benefits of a sweat lodge may greatly outweigh a person’s potential medical risks. Again, a collaboration among participants, traditional healers, and health providers (physicians, nurses, substance abuse counsellors) is necessary. Participants with asthma, diabetes, and arthritis must be made aware that their responses to the conditions of the sweat lodge are not predictable. After consultation with Native healers and Native or non-Native medical providers, individuals might decide to participate on a trial basis. Persons with blood pressure problems or cardiac conditions might attend only one round of the lodge, avoid standing up suddenly, and protect themselves from cold exposure when leaving the lodge. Anyone experiencing dizziness, nausea, chest pain, or palpitations should be encouraged to leave the lodge. They can sit near the entrance to the lodge so they can leave without disturbing the proceedings or risking injury from stepping over the hot stones.
In general, clearing rocks, broken glass, and other hazards in a path from the lodge before dark, and having a flashlight available, can prevent injuries and falls. Participants should avoid eating a heavy meal before a sweat and should drink adequate fluids before and after the lodge.
Authors’ note
Readers who wish to obtain a complete list of references
may contact Dr. Berger at the Lovelace Clinic Foundation. Also, the authors welcome any comments on or additions to this paper, since even a comprehensive literature review of such a broad topic is likely to omit important studies.

Sweat Lodges: A Medical ViewLawrence R. Berger, MD, MPH; and J. Eric Rounds, BS, MA, The Lovelace Clinic Foundation, Albuquerque, New MexicoIntroductionSweat lodges are becoming increasingly popular both within Native American communities and among nonIndians.1-3 In addition to their traditional use for purification of mind, body, and spirit, sweats are now frequently used as a component of substance abuse treatment and rehabilitation programs for incarcerated Native Americans. A resurgent interest in and respect for Native American culture and traditions among the general public, and the growing popularity of New Age spirituality, have also prompted a dramatic rise in the number of people participating in Native American sweat lodges.There is great variation in how sweats are conducted.2,4 Some are led by recognized Native American spiritual leaders, take place over several hours with intense heat, and are restricted to persons with a profound commitment to tradition and ceremony. At the other extreme are sweats that are open to anyone, have no leaders, and are primarily social gatherings. While the spiritual and philosophical issues raised by the proliferation of sweat lodges are important, we focus in this article on the medical aspects. What are the potential health benefits of sweat lodges? What risk factors might prompt individuals to approach sweats with caution? What medical issues deserve further research? To help answer these questions, we conducted an extensive literature review. Relevant articles were identified via searches of Medline (1966-1997), Toxline (1966-1997), Science Citation Index (1966-1997), Sociological Abstracts (1963-1997), Biological Abstracts (1969-1997), Psychological Abstracts (1967-1997), and Carl (Un)Cover (1990-1997). We also searched the World Wide Web using the browsers “Infoseek” and “Excite.”This article reviews the health risks and therapeutic benefits of sweating. Our goals are to stimulate research interest in the therapeutic value of sweat lodges, promote the health and safety of individuals considering participation in regular sweats, and highlight another aspect of traditional, Native American wisdom. We especially hope this information will be of value to health practitioners whose patients may ask for guidance regarding participation in sweats; and to sweat lodge leaders, who should consider the physical and medical condition of individuals, in addition to their emotional and spiritual preparedness, before inviting them to a sweat lodge.This article is consistent with the IHS policy of encouraging “a climate of respect and acceptance in which an individual’s private, traditional beliefs become a part of the healing and harmonizing forces within his or her life.” By discussing the potentially beneficial medical and physical aspects of the sweat lodge, as well as the conditions that might warrant caution in its intensive use, we hope to increase the visibility of, and appreciation for, this powerful activity. In no way is our emphasis on physical health meant to diminish the profound spiritual and ceremonial importance of sweat lodges.Potential Health BenefitsNatural health practitioners have recommended sweat therapy for persons with a variety of ailments, from infectious diseases to insomnia.3,5,6 There is growing scientific support forIn This Issue…69Sweat Lodges: A Medical View75Buckle Up for Life: An Incentive Program80Position Vacancies81Meetings of Interest81NCME Videotapes Available82Native American Medical Literature■their enthusiasm based on laboratory work, clinical studies, and research involving heat chambers and saunas. Clinical studies of Scandinavian sauna-bathing are particularly relevant to sweat lodges. Both are often practiced weekly and involve high temperatures and high humidity generated by throwing water on hot stones, although saunas in the United States often use dry heat, as do some Native American sweat lodges.Anti-infectious. The heat of a sweat lodge is capable of raising core body temperature, creating what might be called a “temporary fever.” In a sauna at 80 degrees Centigrade (C), adults raise their rectal temperature about 1 degree C after 30 minutes.7 There is increasing evidence that mild to moderate elevations of temperature can enhance specific and nonspecific immunity.8-14 Febrile temperatures have been shown to promote the migration of neutrophils, the production of antibacterial substances by leukocytes, and the antiviral activity of interferon.14 An experiment with mice infected with herpes virus provides a dramatic example of improved host defenses: increasing their core temperature by 2 degrees Centigrade improved their survival rate from 0% to 100%.8 Studies in humans have shown that children with chickenpox have a longer time to total crusting of lesions when treated with temperature-lowering doses of acetaminophen, and adults with rhinovirus have more nasal viral shedding when they receive aspirin rather than placebo.9Human sweat contains immunoglobulin-A (IgA) and specific antibodies to such antigens as hepatitis B and tetanus.15,16 There are also many agents in sweat associated with the inflammatory response.17-21 These proteolytic enzymes, histamine, kinin, and interleukins very likely enhance resistance to viral, bacterial, and parasitic infections.10,17,22 They may provide local protection of the skin and prevent the invasion of harmful agents through the skin and into the bloodstream.Certain infections, however, may actually be facilitated by increased body temperature. The best example is recurrent herpes simplex infections.13 So-called “fever blisters” are lesions caused by the recrudescence of latent herpesvirus infections. They occur during natural fevers or artificial elevations of body temperature.Anti-cancer. Hyperthermia appears to be a promising modality for cancer treatment when combined with radiotherapy or chemotherapy, although the experimental body temperatures (41-45 degrees C) are well above those experienced in a sweat lodge.23-24 Yet there may also be anti-cancer benefits to raising body temperature to the febrile range. Elevated temperatures have been shown to retard the proliferation of certain tumor cells, increase the antitumor activity of interferon and interleukins, and enhance the killing efficiency of specific cytotoxic t-lymphocytes.14, 23As in the case of infections, there is reason for caution in concluding that raised body temperature is uniformly helpful in cancer prevention and treatment. Laboratory studies indicate that hyperthermia can cause dysfunction of gene repair mechanisms and reduced natural killer activity of human mononuclear cells.25,26 Also, some animal studies have shown an increase in metastases following whole body heating.27Detoxification. The idea that deleterious “toxins” can be eliminated from the body by sweating is a popular one, as evidenced by these quotes from publications intended for the general public: “Sweating is one of our most important mechanisms of natural healing, since it allows the body to rid itself of unwanted materials”3; “Impurities in many body organs are flushed out as the capillaries dilate and the heart increases its pace”2; “‘Heat stress’…is very effective in releasing fat-stored toxins from the cells.”28 While there is no question that sweat glands are excretory organs, the clinical significance of human sweat as an excretory pathway for specific substances has received little scientific scrutiny.Human sweat is a dilute solution that contains mainly sodium, potassium, chloride, and bicarbonate.29 Urea, amino acids, glucose, magnesium, calcium, lactate, proteins, and enzymes also appear in sweat. The concentration of ammonia in sweat is 20 to 50 times higher than in plasma.30 Sweat appears to be an important excretory pathway for zinc and copper, and possibly other trace metals such as cadmium, manganese, aluminum, lead, iron, and nickel.31,32 Workers occupationally exposed to lead have extremely high levels of lead in sweat even when their blood lead levels are only moderately elevated.33Water-soluble bile pigments are excreted by the sweat glands of patients with severe liver disease.34 Patients with renal failure have elevated sweat potassium concentrations and increased sweating “may play a role in removal of sweat electrolytes from the body.”29 The concentration of urea in sweat is approximately the same as the plasma concentration. This accounts for the occurrence of “urea frost” on the skin of patients with uremia.30Street drugs (such as amphetamines, heroin, cocaine) and their metabolites are excreted in sweat, but usually in nanogram amounts.35-37 Medications, such as antineoplastic drugs, benzodiazepines, iodine, and antibiotics, are detectable in sweat.35,38-41 Ethyl alcohol is secreted in sweat in concentrations that approximate its concentration in blood.20Healthy skin and treatment of skin disorders. Repeated sweat baths may promote healthier skin by several mechanisms including a direct therapeutic effect of heat, increased blood flow to the skin, and the delivery of substances within sweat itself. In a sweat lodge or sauna, the temperature of the skin can rise from 32 degrees C at room temperature to 40 degrees C or higher.42 Heat stress leads to an increase in cardiac output and vasodilation over the entire body surface.43 Blood circulation to the skin can reach up to 8 liters per minute in an adult (from less than one liter per minute at room temperature). As much as 50-70% of the cardiac output may be directed to the blood vessels of the skin (versus 5-10% at room temperature).42,44 This dramatic increase in blood flow means increased perfusion and the delivery of oxygen, immune agents, and other substances to70 THE IHS PROVIDER June 1998■the skin. Wound healing may be accelerated by interleukins, chemokines, and nitrates in sweat that result in the generation of nitric oxide on the skin surface.17,18,45-47Local hyperthermia and/or sauna bathing have been used to treat psoriasis, atopic eczema, warts, scleroderma, pemphigus, pityriasis versicolor, tinea, leg ulcers, fungal and atypical mycobacterial skin infections, and scabies.42,48-50 Sweat urea may function as a natural skin moisturizer.30 The excretion of medications via sweat can improve the treatment of resistant cutaneous fungal infections:For example, orally administered griseofulvin andketoconazole are secreted into sweat, thereby quicklyreaching the stratum corneum where dermatophytes arepresent, bypassing the slow diffusive pathway across theepidermal cell layer… The best way to improve theantifungal effect of these agents is to obtain maximal perspirationwhile the patient is taking the drugs.30Other Conditions. A double-blind study of patients with perennial rhinitis found that raising intranasal temperature by inhalation of saturated hot air (42-44 degrees C) resulted in reduced rhinitis symptoms and increased nasal patency.51 Hot baths 1.5 hours before bedtime resulted in deeper and more restful sleep among a group of women aged 60-72 years with insomnia.52Pain relief and muscle relaxation from sweat baths may be of particular benefit in persons with musculoskeletal injuries, overuse ailments, arthritis and other rheumatic diseases, premenstrual syndrome, and insomnia.53-56 Heat may alleviate pain by releasing endogenous opioids and reducing anxiety.53,57 Heat may promote muscle relaxation by increasing the extensibility of collagen-rich tissues (such as tendons, fasciae, and articular capsules), increasing oxygen delivery to stressed muscles, speeding immune cellular repair, and reducing pain.47,53 The plasma concentration of prolactin increases during heat exposure.58 This physiologic effect, along with the relaxation induced by a sweat bath, might facilitate breast feeding.Potential Health RisksInjuries. Based on conversations with sweat lodge leaders, probably the most common hazards of sweat lodges are falls, lacerations, and abrasions from participants tripping or stepping on objects while walking barefoot to and from the lodge.Acute musculoskeletal disorders. Laboratory studies suggest that higher temperatures can increase the breakdown of articular cartilage and tissues that contain collagen.55,59 In experimental animals, hyperthermia can exacerbate acute inflammation.53 These in vitro studies may explain why some patients with joint and musculoskeletal symptoms complain of increased pain after heat exposure. Several authors recommend that patients with acute inflammatory processes in muscles, joints, or back should not undergo heat stress in the first few days after injury, or while there is ache, swelling, redness, or tenderness at rest.53,54,60Pregnancy and women’s health. A prospective study of over 23,000 women found an increased risk of neural tube defects (spina bifida, anencephaly, or encephalocele) among infants born to women who were exposed to heat during the first trimester of pregnancy. The exposures were in the form of hot tubs, saunas, or fevers.61 This research supports animal studies concluding that heat is teratogenic.61,62 A review of pregnancy and the sauna in Finland concludes that “healthy pregnant women may safely have sauna baths throughout their pregnancy.”63 However, the review notes that the fetal heart rate rises during maternal hyperthermia and thermal stress may induce uterine contractions and lower uterine blood flow.63 Sweat iron loss coupled with a low dietary iron intake may result in a negative iron balance and anemia for women.64 At least one study found a lower sweat volume among females than males.65Dehydration. A person who is dehydrated upon entering a sweat lodge is at risk of heat exhaustion, hypotension, and syncope. Dehydration lowers the sweating rate for a given core temperature, increases heart rate, and decreases cardiacoutput.20,43,66In very hot environments, water losses from sweating can approach two liters per hour.67Male infertility. In otherwise healthy men, increased scrotal temperatures are associated with decreases in sperm count and in the percentage of motile spermatozoa. These abnormalities are reversible when temperatures return to normal. Infertile men are advised to avoid hot environments.68,69 The contraceptive efficacy of a daily mild increase (1-2 degrees C) in testicular temperature during waking hours is under investigation.70Cardiovascular conditions. Individuals with cardiovascular problems (such as hypotension or hypertension, congestive heart failure, or impaired coronary circulation), or who are taking medications which might affect blood pressure, need to exercise caution in exposing themselves to prolonged heat.71,72 During heat waves, chronic cardiovascular diseases are the most common underlying disorders among patients with heat stroke.73 Heat stress causes fluid shifts in the body as a result of both cutaneous vasodilation and fluid loss from sweating. Also, cardiac output increases in order to transfer internal heat to the outside environment via the skin and respiratory system.71,72 The rise in cardiac output (2.8 l/min for every one degree Centigrade increase in body temperature) is primarily due to changes in heart rate (which increases by about 30 beats per minute for each degree increase in internal temperature).43,44Blood pressure usually falls during heat stress as a result of the redistribution of blood volume to skin and away from the splanchnic (gastrointestinal, splenic, and pancreatic), renal, and skeletal muscle circulations.43,44 Decreased coronary perfusion pressure, combined with increased blood viscosity (due to decreased intravascular fluid volume) and increased myocardial oxygen demand from tachycardia, all increase the risk of myocardial ischemia. Conversely, blood pressure mayJune 1998 THE IHS PROVIDER 71■rise dramatically on exposure to cold, such as when a person leaves a sweat lodge on a winter’s day. Sudden cold exposure increases the work of the heart because of the very rapid transitory volume and pressure loads, accelerated heart rate, and increased sympathetic activity. These changes increase the risk of myocardial ischemia and arrhythmias.44,54,72 Changes in circulating blood volume, blood viscosity, and blood pressure also pose a risk for cerebrovascular events (syncope, stroke).Children. When exposed to hot environments, children experience a much more rapid rise in core temperature than adults do. This is reflected in the excess death rate due to heat illness among infants and children during heat waves.74 Higher metabolic rates per unit mass, greater body surface area/mass ratio, and limited circulatory adaptation to increased cardiac demands play a role.7,66,74-76 Maturation of the ability to regulate body temperature by sweating is said to occur only at puberty.66,76 Children’s thinner skin layers (epidermis and dermis) also increase their susceptibility to burns,76a both from the hot steam and heated stones of a sweat lodge.Medications. Sympathomimetic drugs may provoke tachycardia and arrhythmias with heat stress. Atropine, glutethimide, tricyclic antidepressants, phenothiazines, and antihistamines have anticholinergic action that can predispose to syncope and heat stroke.66,73 Diuretics can produce hypovolemia, hyperosmolality, and reduced evaporative water losses through a reduction in sweat rate.67 Barbiturates and beta-blockers can also impair heat loss mechanisms.77,78The Elderly. The ability to maintain core temperature during heat stress decreases with increasing age because of decreased sweat gland function, cutaneous blood flow, and innervation to sweat glands.79,80 Also, elderly individuals may be prone to orthostatic hypotension and need to be cautious to avoid syncope when standing up after a sweat bath.72Diabetes. The impact of sweat bathing on insulin levels is not easily predicted. Subcutaneously injected insulin is absorbed faster than usual in hot environments, probably because of increased cutaneous circulation. At the same time, heat exposure increases the secretion of catecholamines (such as noradrenaline) and possibly other insulin antagonists.54,58 Individuals with neuropathy can experience burns from lack of sensation and an impaired sweating ability.20,81Alcohol abuse. Acute alcohol intoxication poses many hazards in the sweat lodge. Decreased judgement, balance, and coordination can lead to burns and falls. Both alcohol and heat stress dilate peripheral vasculature, increasing the risk of orthostatic hypotension and syncope; and both increase adrenergic activity, predisposing to cardiac arrhythmias.82 Chronic liver disease can lead to abnormal sweating because of autonomic dysfunction.83Asthma. Smoke from cedar, sweetgrass, tobacco, or other plants used in sweat lodges may serve as pulmonary irritants. Humid air has a variable effect on patients with asthma, decreasing forced expiratory volume and airway conductance in some studies and increasing it in others.84-86 Bronchodilators in combination with heat stress may provoke tachycardia and arrhythmias.87Skin disorders. The onset or exacerbation of certain skin disorders (eczema, cholinergic urticaria, acantholytic dermatosis, miliaria) have been linked to heat and sweating.42,88,89 “Heat rash” is caused by the plugging and rupture of sweat glands following sweating-induced skin maceration.77 Some skin disorders (e.g., psoriasis, miliaria rubra) can occlude sweat ducts, substantially reducing sweating.20 Sunburn decreases the responsiveness of the sweat gland and its capacity to deliver sweat to the skin surface.66Kidney disease. Patients with chronic renal failure often complain of dry skin and pruritus, which may be due to the atrophy of sweat glands, elevated antidiuretic hormone, and a decreased sweating response.29,90 Excessive sweating may affect electrolyte balance, since patients with advanced renal failure have higher sweat concentrations of potassium.29Neurologic disorders. Although some patients with multiple sclerosis (MS) show improvement after warming, about 80% suffer neurological deterioration (such as muscular weakness and ocular abnormalities) when subjected to heat. Until the early 1980s, the “hot bath test” was used in diagnosing the disease. The test was largely abandoned “because it sometimes resulted in permanent neurologic deficits in MS patients.”91 Patients with Parkinson’s disease can exhibit a range of sweating disorders.92Patients with peripheral neuropathies (e.g., from diabetes, alcoholism, Guillain-Barre syndrome, leprosy) that impair sensation are obviously at risk for serious burns in the sweat lodge, both from hot steam and contact with the heated stones.Other Conditions. Reduced ability to sweat can place a person at risk of heat stroke during a sweat lodge. Conditions associated with impaired sweating include extensive scarring from burns, total body electron beam irradiation, diabetes with neuropathy, Parkinsonism, multiple sclerosis, cervical spine lesions, central nervous system tumors, hypothyroidism, amyloidosis, injuries, or hemorrhages.29,92 Untreated hyperthyroidism can increase core heat production by up to 400%, greatly increasing the risks of heat exposure.73,78Conclusions and RecommendationsThe potential health benefits of regular participation in Native American sweat lodges are numerous. This is not at all surprising, given that sweat bathing has been practiced for thousands of years in many cultures throughout the world. What is very surprising is the scarcity of research about the practice, especially in light of the growing worldwide interest in complementary healing. Promising areas for research are the value of sweat bathing for preventing and treating infectious diseases (especially with the rise in antibiotic-resistant infections); treating arthritis (where heat can have paradoxical effects on inflammation); treating skin disorders (where remarkable increases in skin blood flow enhance both natural immunity and the delivery of medications); treating and reha72THE IHS PROVIDER June 1998bilitating individuals with alcohol and other substance abuse disorders (for example, there are no studies estimating the amounts of drug metabolites excreted during profuse and prolonged sweating); and preventing cancers, their metastases, and post-treatment relapses. Research is especially urgent where current evidence is conflicting, such as the impact of elevated temperatures on tumor behavior, the immune system, and joint disorders.The sacred and ceremonial nature of traditional sweat lodges does not mean their physical effects cannot be evaluated. For example, the value of sweat lodges as an adjunct to alcohol treatment programs could be assessed by comparisons among treatment sites, perhaps with a crossover design. Furthermore, disregarding spiritual aspects, the sweat lodge and the sauna are remarkably similar physically, and possibly have an identical origin.93 Conditions of heat and humidity in the sweat lodge can be duplicated in the sauna, making possible randomized trials of individuals with specific medical conditions. Any research involving sweat lodges per se (as opposed to studies of sweating in clinical or laboratory settings) must necessarily involve a collaboration among participants, traditional healers, and investigators. What factors, if any, do traditional healers or Tribes think are important to study? How might studies be undertaken with full respect for traditional values and practices? How would results be shared? The ethical and cultural implications of such research are as important to consider as the cultural issues.The potential health hazards of sweat lodges need not exclude individuals with mild or moderate risk factors from participation. The social, spiritual, and psychological benefits of a sweat lodge may greatly outweigh a person’s potential medical risks. Again, a collaboration among participants, traditional healers, and health providers (physicians, nurses, substance abuse counsellors) is necessary. Participants with asthma, diabetes, and arthritis must be made aware that their responses to the conditions of the sweat lodge are not predictable. After consultation with Native healers and Native or non-Native medical providers, individuals might decide to participate on a trial basis. Persons with blood pressure problems or cardiac conditions might attend only one round of the lodge, avoid standing up suddenly, and protect themselves from cold exposure when leaving the lodge. Anyone experiencing dizziness, nausea, chest pain, or palpitations should be encouraged to leave the lodge. They can sit near the entrance to the lodge so they can leave without disturbing the proceedings or risking injury from stepping over the hot stones.In general, clearing rocks, broken glass, and other hazards in a path from the lodge before dark, and having a flashlight available, can prevent injuries and falls. Participants should avoid eating a heavy meal before a sweat and should drink adequate fluids before and after the lodge.Authors’ noteReaders who wish to obtain a complete list of referencesmay contact Dr. Berger at the Lovelace Clinic Foundation. Also, the authors welcome any comments on or additions to this paper, since even a comprehensive literature review of such a broad topic is likely to omit important studies.

Source: http://www.ihs.gov/provider/documents/1990_1999/PROV0698.pdf

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