ReviewBenefits and risks of sauna bathing
Section snippets
Methods
We searched four databases using search words “sauna,” “Finnish bath,” and MeSH term “Baths, Finnish.” The databases were Medline (1966 to 2000, n = 336 documents in English or German), Embase (1974 to 2000, n = 61), Biosis Previews (1970 to 2000, n = 135), and Medic (1978 to 2000, n = 6). We supplemented our search by examining citations in the articles. Of the 271 documents that provided information on the chosen topics (sauna and the cardiovascular system, lungs, rheumatic diseases, skin,
The sauna (finnish bath)
Unlike the Turkish bath, the sauna (or Finnish bath) has dry air and a high temperature (4). The basic modern sauna is an unpainted, wood-paneled room with wooden platforms and a rock-filled electric heater. The walls are made of spruce or pine, and the benches are made of obeche, spruce, or aspen because these types of wood are less hot to sit on. The size of a sauna is at least 3 m2 to encourage the correct balance between heat, humidity, and ventilation. The recommended temperature is 80°C
Cardiovascular effects
The cardiovascular effects of sauna bathing have been reviewed earlier 7, 9, 10, 11, 12 and are summarized in Table 1. Skin temperature increases rapidly to about 40°C 5, 9, 13, 14, whereas the increase in rectal temperature depends on heat exposure 15, 16, 17. Sweating begins quickly and reaches its maximum at about 15 minutes, with an average total secretion of 0.5 kg 6, 9, 18. Skin blood flow is increased from 5% to 10% so it becomes 50% to 70% of the cardiac output, while blood flow to
Sauna and drugs
Vanakoski et al 52, 53 have reviewed the effects of heat exposure on the pharmacokinetics of drugs. The effects of hyperthermia on the absorption, distribution, and elimination (54) of orally administered drugs were shown to be minor in studies with propranolol (47), captopril (47), midazolam 55, 56, ephedrine (55), and tetracycline (57). Increased skin blood flow during sauna did, however, enhance the systemic absorption of transdermally administered nitroglycerin (58) and nicotine (59). The
Sauna and the lungs
Sauna bathing decreases pulmonary congestion and increases the vital capacity, tidal volume, minute ventilation, and forced expiratory volume of the lungs 9, 62. Patients with asthma or chronic bronchitis report that sauna bathing improves their breathing (62). Twelve patients with obstructive pulmonary disease who took sauna as a part of their rehabilitation program also demonstrated improved lung function (63). Other data, however, reveal no such changes 64, 65. Studies by Ernst et al (66)
Sauna and rheumatic disease
Sauna bathing has been used as thermal therapy to treat pain and other symptoms of rheumatic disease, although clinical studies are limited. In studies based on interviews of 70 patients (73) and 119 patients (74) with rheumatoid disease, 40% to 70% of participants reported that sauna bathing alleviated pain and improved joint mobility. Approximately half of the patients experienced exacerbated pain on the day after sauna bathing but reported that this pain could often be prevented by a cool
Sauna and the skin
In general, sauna bathing is harmless for the skin. Repeated stays in the sauna (30 minutes 4 times per day for 7 days) cause no withering of the skin and no change in transepidermal water loss 76, 77. Although sauna bathing is seldom used as a therapy for skin disease, it may benefit patients with psoriasis by helping to keep skin lesions free of thick scales (77). In some atopic subjects and patients with cholinergic urticaria, sauna bathing may cause intense itching of the skin (77). Contact
Sauna and hormonal changes
Sauna bathing activates the sympathetic nervous system, the renin-angiotensin-aldosterone system, and the hypothalamus-pituitary-adrenal hormonal axis. The hormonal changes related to sauna use are summarized in Table 2. Changes in the endocrine system are brief and reversible, with no permanent effects (81).
Fertility
Sauna bathing does not influence fertility. In men, serum concentrations of testosterone and gonadotropins do not change even after repeated sauna use 82, 83, 84, 85. Prolactin concentration increases temporarily in both men and women during sauna bathing 82, 83, 84, 85, 86, 87. A few studies have reported decreased sperm count or decreased sperm movement after sauna bathing 88, 89, 90. Finnish men, however, have high sperm counts 91, 92, and the time to pregnancy (a sensitive indicator of
Sauna and children
Healthy children who are accustomed to sauna bathing tolerate it well when their parents supervise bathing time and temperature. In Finland, children typically take sauna once per week with their parents, who adjust the conditions according to each child’s reaction (109). Children usually have shorter sauna baths (5 to 10 minutes) than their parents and sit on the lower bench where the temperature is not as hot (110).
Jokinen et al 111, 112, 113, 114 studied the effects of sauna bathing in 81
Summary
For most healthy people, as well as for most patients with stable coronary heart disease, sauna bathing is well tolerated and safe. The physiological (Table 1) and hormonal (Table 2) changes that occur during sauna bathing are transient. Sauna bathing does not cause drying of the skin 76, 77. The effects of hyperthermia on the pharmacokinetics of several orally administered drugs are minor 47, 54, 55, 56, 57. Sauna bathing does not lower fertility in men or women 91, 92, 93 nor is it harmful in
Acknowledgements
The excellent help of Marja Snyder in the literature search is greatly appreciated. We also thank Ellen K. Shair, MA, for editing the manuscript.
References (130)
Heart-attacks and the sauna
Lancet
(1976)- et al.
Sauna-induced myocardial ischemia in patients with coronary artery disease
Am J Med
(1999) - et al.
Comparison of blood pressure response to heat stress in sauna in young hypertensive patients treated with atenolol and diltiazem
Am J Cardiol
(1989) - et al.
Increased uptake of transdermal glyceryl trinitrate during physical exercise and during high ambient temperature
Am Heart J
(1986) - et al.
Effect of exposure to sauna heat on neuropathic and rheumatoid pain
Pain
(1992) Decreased fertility in Britain compared with Finland
Lancet
(1996)- et al.
Maternal hyperthermia as a possible cause of anencephaly
Lancet
(1978) Traditional use of the sauna for hygiene and health in Finland
Ann Clin Res
(1988)The sauna and bathing in different countries
Ann Clin Res
(1988)- Schoolfield GC, ed. The Kalevala, Epic of the Finnish People. [Translated by Eino Friberg.] Helsinki, Finland: Otava;...
Sauna—made in Finland
The secret of good “löyly”
Ann Clin Res
Human thermoregulation in sauna
Ann Clin Res
Facts and fables about sauna
Ann NY Acad Sci
The sauna and body fluid balance
Ann Clin Res
Special review. Part I. Physiological effects of extreme heat as studied in the Finnish “sauna” bath
Am J Phys Med
Special review. Part II. Physiological effects of extreme heat as studied in the Finnish “sauna” bath
Am J Phys Med
Man in the sauna
Ann Clin Res
Sauna bather’s circulation
Ann Clin Res
Sauna, shower, and ice water immersion. Physiological responses to brief exposures to heat, cool, and cold. Part III. Body temperatures
Arct Med Res
Heat exposure elevates plasma immunoreactive growth hormone-releasing hormone levels in man
J Clin Endocrinol Metab
Passive heat exposure leads to delayed increase in plasma levels of atrial natriuretic peptide in humans
J Appl Physiol
Some cardiovascular and metabolic effects of repeated sauna bathing
Acta Physiol Scand
Sauna, shower, and ice water immersion. Physiological responses to brief exposures to heat, cool, and cold. Part I. Body fluid balance
Arct Med Res
Effects of the Finnish sauna on circulation. Studies on healthy and hypertensive subjects. Helsinki, Finland. Thesis
Ann Med Exp Biol Fenn
Sauna, shower, and ice water immersion. Physiological responses to brief exposures to heat, cool, and cold. Part II. Circulation
Arct Med Res
Cardiovascular effects of the sauna
Am J Phys Med
The heart and the cold
Ann Clin Res
Cardiac arrhythmias, sudden death and the Finnish sauna bath
Adv Cardiol
Sudden death and physical activity
Cardiology
Sudden coronary death in middle age and characteristics of its victims in Finland, a prospective population study
Acta Med Scand
Arrhythmias and other cardiovascular responses during Finnish sauna and exercise testing in healthy men and post-myocardial infarction patients
Acta Med Scand
The Finnish sauna and cardiovascular diseases
Ann Clin Res
Die Saunatherapie bei koronarer Herzkrankheit mit Hypertonie nach Bypassoperation, bei Herzwand-Aneurysma-Operation und bei essentieller Hypertonie. [Effects of saunatherapy on patients with coronary heart disease with hypertension after bypass operation, after heart aneurysm operation and essential hypertonia]
Z Gesamte Inn Med
Möglichkeiten des Einsatzes der Sauna in der Langzeitbehandlung von hypertonen Herz-Kreislauf-Regulationsstörungen - ein Vergleich zur Kinesiotherapie. [Application of sauna for long-term treatment of hypertension in cardiovascular disorders—a comparison with kinesiotherapy]
Schweiz Rundsch Med Prax
Der Einsatz der Lauf- und Saunatherapie zur Rehabilitation von hypertonen IHK-Patienten nach aortokoronarer Venenbypassoperation (ACVB) unter besonderer Berucksichtigung der Hämodynamik. [Running and sauna as therapy in the rehabilitation of hypertensive patients with IHD after aortocoronary venous bypass surgery with special regard to hemodynamics]
Z Kardiol
Sind Schwimmen und Sauna bei der Rehabilitation von Herzpatienten gefährlich? [Are swimming and sauna hazardous in the rehabilitation of heart patients?]
Schweiz Med Wochenschr
EKG-Untersuchungen an Infarktrehabilitanden in der Sauna. [ECG studies in the sauna on post-infarction patients undergoing rehabilitation]
Z Physiother
Cardiac responses to thermal, physical, and emotional stress
BMJ
If you can’t stand the heat, get out of the kitchen
Am J Med
The sauna and alcohol
Ann Clin Res
Alcohol and sauna bathingeffects on cardiac rhythm, blood pressure, and serum electrolyte and cortisol concentrations
J Intern Med
Effects of alcohol ingestion on cardiac rhythm in patients with ischaemic heart disease
Ann Clin Res
Alcohol and new onset atrial fibrillationa case-control study of a current series
Br Heart J
Unerwartete und plötzliche Tode in der finnischen Sauna. [Unexpected and sudden deaths in the Finnish sauna]
Beitr Gerichtl Med
Alcohol consumption and sudden coronary death in middle-aged Finnish men
Acta Med Scand
Hyperthermia deaths in Finland in 1970–86
Am J Forensic Med Pathol
Das Verhalten von zentraler und peripherer Hämodynamik unter isometrischer und dynamischer Belastung bei Hypertonikern unter regelmässiger Saunabehandlung. [Changes of central and peripheral hemodynamics during isometric and dynamic exercise in hypertensive patients before and after regular sauna therapy]
Z Kardiol
Effects of propranolol and guanethidine on the circulatory adaptation in the Finnish sauna
Ann Clin Res
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2022, Neurobiology of AgingCitation Excerpt :Hypertension is associated with a higher risk of developing AD (Edwards Iii, et al., 2019; Glodzik, et al., 2014), and hypertension in AD mouse models was shown to increase tau phosphorylation (Shih, et al., 2018). As sauna bathing can decrease blood pressure (Hannuksela and Ellahham, 2001; Winterfeld, et al., 1993), it could therefore indirectly lower tau phosphorylation by modulating blood pressure. However, we observed that tau was dephosphorylated in neuronal cells exposed to mild hyperthermia, suggesting that this treatment can lead to neuronal tau dephosphorylation per se, independently of potential blood pressure effects.