Sighing and Meaning of Sighs: Dysregulation of Breathing
Definition of sighs (how to define sighs)
Sighing is defined as an involuntary inhalation (inspiration) that is 1.5-2 times greater than the usual tidal volume. Some studies suggest that a sigh should be defined as 1.5 times increase in the personal typical tidal volume (Leiner & Abramowitz, 1958). Some other authors suggested another definition of a sigh: it should be at least as twice as deep as the person's average inhalation (Wilhelm et al, 2001; Caughey et al, 1943).
Respiratory mechanics of sighs
Sighing is usually done using primarily the upper chest, dorsal muscles, or upper sternum (Lum, 1975; Gallavardin, 1925; Leiner & Abramowitz, 1958) and is a sign of chest or thoracic breathing (Katagiri et al, 1998; Lum, 1975; Lum, 1981; Gallavardin, 1925; Leiner & Abramowitz, 1958).
Sighing during sleep
Sighing can be present during sleep in normal adults (Perez-Padilla et al, 1983) and infants (Gerard et al, 2002). This study on sighs during sleep in adults (Perez-Padilla et al, 1983) discovered that all 12 normal adults had sighs during their night sleep, from 1 to 25 sighs per night.
Sighing means inhaling a lot and reduced brain O2
After analyzing hundreds of sighs in more than 80 people with mostly respiratory problems* (see the note below), Leiner & Abramowitz (1958) found that in more than 80% of people the volume of air for one sigh was more than 1,300 ml and in some people up to 2.5-3 liters, with an average of about 1,700 ml per sigh for this group. These authors also discovered that, for the majority of subjects (more than 82%), the amount of air for one sigh was ranging from 40% to 60% of their vital capacity (the difference between the maximum inhalation and maximum exhalation).
This produces a similar effect on brain O2 content as light hyperventilation.
The normal vital capacity in healthy people is 4,500 ml which indicates that this group of subjects had reduced vital capacity (due to presence of respiratory problems). Hence, this study suggests that the average sighing volume in normal adults (with no lung pathologies) is over 2,000 ml. The normal tidal volume is 500 ml. This suggests that a typical adult's sigh is 4 times larger, a lot more, than the normal tidal volume.
Meaning of sighing: health problems
Sighing is generally regarded as a symptom of abnormal or dysregulated breathing since normal breathing in healthy subjects is regular or periodic (i.e., without sighing). Excessive or frequent sighing is considered a sign of panic disorder (Abelson et al, 2001; Schwartz et al, 1996; Wilhelm et al, 2001a; Wilhelm et al, 2001b), anxiety states (Lum, 1981), low back pain (Chaitow, 2004), nervous disturbance (Rechnitzer et al, 1929), dyspnea (Magarian et al, 1983), neurocirculatory asthenia (cardiovascular disease) and nervous instability in young women (White & Hahn, 1929), and respiratory neurosis (Christie, 1935). Some studies point that people with depression often suffer from excessive sighing. In comparison with normal and healthy subjects, sighing is more common in patients with rheumatoid arthritis who have depression (Robbins et al, 2011). Hence, in most cases, frequent or excessive sighing means being under stress.
However, sometimes excessive sighing and/or yawning can take place due to resetting of the respiratory center (e.g., after the meal is digested, after or even during physical exercise, and so forth). In such cases, one should hold the breath after their usual exhalation (perform the body-oxygen test) and do Buteyko reduced breathing exercise with air hunger for 1-2 minutes to stop sighing and increase brain oxygenation.
Respiratory causes of frequent sighing
While many causes of sighing have been suggested, the most impressive evidence relates to the link between sighing and typical symptoms of hyperventilation (Aljadeff et al, 1993; Brashear, 1983; Okel BB & Hurst, 1961; Saltzman et al, 1963). Many other researchers consider sighing as a hallmark and classical symptom - or form - of hyperventilation (Bass & Gardner, 1985; Berczeller, 1993; Brashear, 1983; Fraser & Pare, 1979; Gliebe PA & Auerback, 1944; Howell, 1990; Ker, 1937; Lum, 1975; Lum, 1981; Magarian et al, 1983; Rice et al, 1950).
Blashear (1983) in his article in Lung titled "Hyperventilation Syndrome" suggested that physicians should regard occasional sighing as a subtle clue to presence of hyperventilation syndrome. Hence, decades of clinical research suggest that hyperventilation is the cause of sighing.
Some researchers revealed that the sigh rate was higher during conditions of relief compared to conditions of stress (Vlemincx et al, 2009), while later, in another study, they found that sighing could be triggered by both mental load and recovery from the attention task (Vlemincx et al, 2011). Sighs can be an expression of an activity, intention or desire that has to be discarded (Teigen, et al, 2008).
When infants are not swaddled, they have increased frequency of sighs during sleep (Gerard et al, 2002). This is probably due to the fact that swaddling restricts ventilation, prevents chest breathing, increases arterial CO2 and cellular O2 concentrations, and makes breathing more regular.
Sighing is sometimes thought to be caused by a spasm of the diaphragm (Gallavardin, 1925; Katagiri et al, 1998; Leiner & Abramowitz, 1958). Indeed, chest breathing means poor diaphragm function with insufficient stimulation of lung tissue and stretch receptors located in the lower parts of the lungs. Therefore, sighing can provide some relief or solution to these problems. However, these problems are natural effects of hyperventilation.
Hyperventilation leads to alveolar hypocapnia and reduced oxygenation of the diaphragm. Furthermore, arterial hypocapnia (CO2 deficiency in the arterial blood) leads to spasms in all muscles of the human body, including the diaphragm (see CO2 links below).
Hence, various causes of hyperventilation, such as supine sleep, mouth breathing, stress, anxiety, overeating, overheating, and poor posture, can intensify sighing. It makes sense then that sighing is often accompanied by other symptoms of hyperventilation, such as dyspnea (or shortness of breath), breathlessness (or heavy and deep breathing), yawning, and coughing. These observations also support the idea about the key role of overbreathing in the pathophysiology of sighing. Therefore, excessive or frequent sighing means that a person is hyperventilating.
Since the overwhelming majority of modern people are hyperventilators and chest breathers (see links below), most modern studies cannot shed more light on the root causes of sighing, unless their subjects retrain and normalize their automatic breathing patterns.
Effects of occasional sighs
Even several very deep and fast breaths cannot improve oxygenation of the arterial blood (which is equal to 98-99% for tiny normal breathing). The main effect of frequent or excessive sighing is hypocapnia (lack of CO2) in the lungs, arterial blood and body cells. Many authors suggest that markedly reduced arterial-CO2 tension could be maintained with very little effort with only an occasional sigh superimposed on the normal breathing pattern (Brashear, 1983; Okel BB & Hurst, 1961; Saltzman et al, 1963). Hence, even occasional sighing means chronic hyperventilation and a reduced oxygen level in cells, while frequent or excessive sighing produces devastating effects on the main gases (CO2 and O2) in the brain, heart and other vital organs.
Many people with dyspnea (breathlessness) testify that sighing brings some relief to their respiratory muscles. This relief may relate to the mechanical effects of sighing on the diaphragm and other respiratory muscles. Several studies have found that artificial sighs, during mechanical ventilation of various lung patients, have positive effects on oxygenation of their arterial blood and diminished viscoelastic impedance.
Treatment of sighing: increase body O2
People with sighing have less than 20 seconds for the body-oxygen test. If they achieve more than 30 s for the body-oxygen test, they will be free from this symptom.
Sighing disappear very quickly with the application of resistive breathing devices (such as the Frolov device, Samozdrav, Amazing DIY breathing device, and many others) since they provide a double positive effect on the causes of sighing. These devices increase CO2 levels in airways and stimulate the lungs and respiratory muscles. In addition, correct physical exercise and other lifestyle changes (in the Section Learn) are necessary for complete remission of sighing.
* The main health problems in this study of sighs (Leiner & Abramowitz, 1958) were tuberculosis, tuberculosis pleurisy, emphysema, bronchogenic carcinoma, sarcoidosis, hemoptysis, asthma, bronchiectasis, arteriosclerotic heart disease, rheumatic heart disease, and cor pulmonale.
Abelson JL, Weg JG, Nesse RM, Curtis GC, Persistent respiratory irregularity in patients with panic disorder, Biol Psychiatry, 2001 Apr 1; 49(7): 588-95.
Aljadeff G, Molho M, Katz I, Benzaray S, Yemini Z, Shiner RJ, Pattern of lung volumes in patients with sighing breathing, Thorax. 1993 Aug; 48(8): 809-11.
Bass C, Gardner WN. Respiratory and psychiatric abnormalities in chronic symptomatic hyperventilation. BMJ 1985; 290: 1387-90.
Berczeller PH, Hyperventilation and sighing, Hosp Pract (Off Ed). 1993 Jul 15; 28(7): 37-41.
Brashear RE, Hyperventilation syndrome, Lung 1983, 161: 1, 257-273.
Caughey JL, Jr, Analysis of Breathing Patterns, 1943, Am. Rev. Tuberc., 48: 382.
Chaitow L, Breathing pattern disorders (BPD), motor control, and low back pain, J of Osteop Med, 2004, 7(1): 34-41.
Christie RV, Some types of respiration in the neuroses, Q J Med, 1935, 4: 427-432.
Fraser RG, Pare JAPP, Diagnosis of diseases of the chest, 2nd ed., vol. 3. Philadelphia: Saunders, 1979: 1944-5.
Gallavardin: Les Angines de Poitrine, Paris, 1925, p. 100, quoted by Baker M, Sighing Respiration as Symptom, Lancet, 1934, 1: 174.
Gerard CM, Harris KA, Thach BT, Spontaneous arousals in supine infants while swaddled and unswaddled during rapid eye movement and quiet sleep, Pediatrics, 2002 Dec; 110(6): e70.
Gliebe PA & Auerback A, Sighing and other forms of hyperventilation simulating organic disease, J Nerv Ment Dis 1944, 99: 600-615.
Howell JBL. Behavioral breathlessness. Thorax 1990;45: 287-92.
Katagiri H, Katagiri M, Kieser TM, Easton PA, Diaphragm function during sighs in awake dogs after laparotomy, Am J Respir Crit Care Med, 1998 Apr; 157(4 Pt 1): 1085-92.
Ker WJ. Some physical phenomena associated with the anxiety states and their relation to hyperventilation. Ann Intern Med 1937;2:962.
Leiner GC & Abramowitz S, The symptom of sighing: physiologic and pathologic
Diseases of Chest, 1958 Jul; 34(1): 60-72.
Lum, LC, Hyperventilation: The Tip of the Iceberg, Journal of Psychosomatic Research, 1975, 19: 375-83.
Lum LC, Hyperventilation and anxiety state, J. R. Soc. Med. 1981, 74.
Magarian GJ, Middaugh DA, and Linz DH, Hyperventilation syndrome: a diagnosis begging for recognition, West J Med. 1983 May; 138(5): p. 733–736.
Okel BB & Hurst JW, Prolonged hyperventilation in man, Arch Intern Med 1961, 108: 757-762.
Perez-Padilla R, West P, Kryger MH, Sighs during sleep in adult humans, Sleep.
1983; 6(3): 234-43.
Rice RL. Symptom patterns of the hyperventilation syndrome, Am J Med 1950; 8: 691.
Robbins ML, Mehl MR, Holleran SE, Kasle S, Naturalistically observed sighing and depression in rheumatoid arthritis patients: a preliminary study, Health Psychol. 2011 Jan; 30(1): 129-33.
Saltzman HA, Heyman A, Sieker HO, Correlation of clinical and physiologic manifestations of sustained hyperventilation, N Engl J Med 1963, 268: 1431-1436.
Schwartz GE, Goetz RR, Klein DF, Endicott J, Gorman JM, Tidal volume of respiration and "sighing" as indicators of breathing irregularities in panic disorder patients, Anxiety 1996; 2(3): 145-8.
Teigen KH, Is a sigh "just a sigh"? Sighs as emotional signals and responses to a difficult task, Scand J Psychol. 2008 Feb;49(1):49-57.
Vlemincx E, Van Diest I, De Peuter S, Bresseleers J, Bogaerts K, Fannes S, Li W, Van Den Bergh O, Why do you sigh? Sigh rate during induced stress and relief, Psychophysiology, 2009 Sep; 46(5): 1005-13.
Vlemincx E, Taelman J, De Peuter S, Van Diest I, Van den Bergh O, Sigh rate and respiratory variability during mental load and sustained attention, Psychophysiology, 2011 Jan; 48(1): 117-20.
White PD, Hahn RG, The symptom of sighing in cardiovascular diagnosis with spirographic observations, Am J Med Science, 1929, 177: 179-188.
Wilhelm FH, Trabert W, Roth WT, Characteristics of sighing in panic disorder, Biol Psychiatry 2001a, 49(7): 606-14.
Wilhelm FH, Gerlach AL, Roth WT. Slow recovery from voluntary hyperventilation in panic disorder Psychosom Med 2001b, 63(4): 638-49.
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