The Sigh and Meaning of Sighing - Breath Dysregulation: Low CO2
Definition of sighs (how to define sighing)
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 causes 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,
Sighs 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.
A sigh means inhaling a lot and reduced brain CO2 and oxygen
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
This produces a similar effect on brain O2 content as light hyperventilation.
The normal vital capacity in healthy people is 4,500 ml
which indicate that this group of subjects
had reduced vital capacity (due to the 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.
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 out 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
However, sometimes excessive sighing and/or yawning can take place due to the
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 sighs
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).
(1983) in his article in Lung titled "Hyperventilation Syndrome"
suggested that physicians should regard occasional sighing as a subtle clue to the
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 the 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 the 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).
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 (shortness
of breath), breathlessness (heavy and deep breathing), yawning, and coughing.
These observations also support the idea about the key role of overbreathing in
of sighing. Therefore, excessive or frequent sighing means that a person is
The overwhelming majority of modern people are hyperventilators and chest
breathers (see links below). Therefore, most modern studies cannot shed more light on the root causes of sighing since these studies investigate people who already suffer from overbreathing.
Effects of occasional sighs
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 sighs: increase body O2
You can discover which criteria helps to get rid of problems with sighing
for good. I tested this on hundreds of my students. These details are provided
as your bonus content below.
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* 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.