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- mise à jour
du
- 18 août
2025
- Front
Med (Lausanne)
- 2025;12:1596512.
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- An
unusual case of yawning during sleep
associated
- with
sleep bruxism and obstructive sleep
apnea
- Michalek M, Marschollek K, Kuliczkowski
W,
- Waliszewska-Prosot M, Wojakowska A,
- Madziarska K, Martynowicz H.
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- Abstract
- The current case report presents an unusual
coincidence of yawning and sleep bruxism during
sleep in a patient with obstructive sleep apnea
(OSA). Both conditions were previously defined
in the literature as challenging,
multidisciplinary problems with complex and
little-known pathogenesis. A 71-year-old man
with a history of coronary artery disease
underwent videopolysomnography (vPSG) due to the
suspicion of OSA. vPSG results confirmed severe
obstructive sleep apnea, sleep bruxism, and
frequent episodes of yawning during sleep.
Therapeutic intervention included positive
airway pressure therapy and resulted in the
resolution of apneic events. Interestingly, PAP
titration also reduced the frequency of episodes
of sleep bruxism and yawning. Results of the
current case report suggest a temporal
relationship between desaturation and yawning
episodes, thus indicating the hypoxic basis for
this behavior. Resolution of yawning after PAP
therapy appears consistent with this theory. An
instrumental approach to OSA diagnosis
supplemented by video-recording allowed the
diagnosis of the unusual presence of yawning
during sleep.
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- Résumé
- Le présent rapport de cas
présente une coïncidence
inhabituelle de bâillements et de bruxisme
pendant le sommeil chez un patient souffrant
d'apnée obstructive du sommeil (AOS). Ces
deux pathologies ont été
précédemment définies dans
la littérature comme des problèmes
difficiles et multidisciplinaires dont la
pathogénie est complexe et peu connue. Un
homme de 71 ans ayant des
antécédents de coronaropathie a
subi une vidéopolysomnographie (vPSG) en
raison d'une suspicion de SAOS. Les
résultats de la vPSG ont confirmé
l'existence d'une apnée obstructive du
sommeil sévère, d'un bruxisme
pendant le sommeil et de fréquents
épisodes de bâillements pendant le
sommeil. L'intervention thérapeutique a
consisté en une thérapie par
pression positive des voies aériennes et
a permis de résoudre les épisodes
apnéiques. Il est intéressant de
noter que le titrage de la pression positive a
également réduit la
fréquence des épisodes de bruxisme
et de bâillements pendant le sommeil. Les
résultats du présent rapport
suggèrent une relation temporelle entre
la désaturation et les épisodes de
bâillements, indiquant ainsi la base
hypoxique de ce comportement. La
résolution des bâillements
après le traitement par PAP semble
cohérente avec cette théorie. Une
approche instrumentale du diagnostic du SAOS
complétée par un enregistrement
vidéo a permis de diagnostiquer la
présence inhabituelle de
bâillements pendant le sommeil.
-
-
 -
- 1 Introduction
- This is a case report of a patient diagnosed
with obstructive sleep apnea (OSA) and sleep
bruxism (SB) with concomitant yawning during
sleep. To our best knowledge, no previous
studies have shown the temporal relationship
between yawning and SB. Both behaviors, SB and
yawning, are considered sleep-related, and both
are still insufficiently explored. SB affects
approximately 21% of the global population, with
some discrepancies depending on the diagnostic
criteria and assessment methods (1). In
contrast, yawning during sleep is a very rare
physiological behavior observed across various
sleep stages; however, specific prevalence data
in the general population remain limited.
-
- Several theories have been proposed to
understand the role of yawning, some focusing on
thermoregulation, others on blood oxygenation,
while the implications of SB remain vague.
- Although yawning is a widely observed
phenomenon, its role is still unclear. Several
assumptions were reported in the literature to
address this issue. Over time, authors suggest
that yawning is linked with the thermoregulatory
process, brain cooling, blood oxygenation,
arousal mechanism and alertness, non-verbal
communication or social aspects, and stress
(24).
-
- The most important theoretical and
conceptual frameworks for sleep bruxism indicate
that this phenomenon has a wide and relevant
impact on oral and general health. Sleep
bruxism, which is defined as repetitive
masticatory muscle activity during sleep (5, 6),
has been previously linked with headache (7),
obstructive sleep apnea (8), perceived stress
(9), and masticatory muscle pain (10). Its
multifactorial etiology remains insufficiently
explored, but recent studies highlighted the
role of genetic predisposition (11) and
environmental and psychosocial risk
factors.
-
- Our case report aims at showing yawning and
sleep bruxism as challenging, multidisciplinary
problems with multifactorial, complex, and
little-known pathogenesis.
-
- 2 Case description
- 2.1 Patient information
- A 71-year-old man suspected of having OSA
was admitted to the Department of Internal
Medicine, Occupational Diseases, Hypertension,
and Clinical Oncology at the Wroclaw Medical
University in Poland to undergo polysomnography.
The patient was initially referred to the Sleep
Laboratory from the Cardiology Unit. During the
medical interview, typical symptoms of OSA,
including loud snoring, witnessed apneas during
sleep, and frequent awakenings from sleep, were
reported by the patient.
-
- 2.2 Medical history
- The patient's medical history included
hospitalization due to acute coronary syndrome
(NSTEMI) about 1 year before admission to the
Sleep Laboratory. He underwent percutaneous
cardiovascular intervention, including
angioplasty with drugeluting stent implantation
(PCI RCA + DES). Other comorbidities involved
arterial hypertension, prediabetic fasting blood
glucose, hypercholesterolemia, benign prostate
hyperplasia, and nicotinism in the past.
Currently applied drugs involve acetylsalicylic
acid 75 mg, pantoprazole 20 mg, ramipril 5 mg,
and atorvastatin 80 mg.
-
- 2.3 Informed consent
- The patient signed a consent form and
participated in the interview, physical, and
instrumental examination voluntarily. The study
was approved by the local Ethics Committee (no.
KB-523/2021) and was conducted following the
principles of the Declaration of Helsinki.
-
- 2.4 Clinical findings
- The patient's physical examination was
within normal limits. The estimated BMI was
26.42 kg/m?. Vital signs at admission were as
follows: blood pressure 121/75 mmHg, heart rate
68/min regular, respiratory rate 14/min, and
body temperature 36.9°C. Patient was
well-developed, well-nourished, appeared to be
of stated age, alert, and fully oriented. Recent
and remote memory were intact. He had good
insight and cognitive function, without aphasia,
dysarthria, or hoarseness. Lips had normal
color, without lesions. Teeth were present, and
dental hygiene was moderate. Gingiva and mucous
membranes were pink without bleeding, lesions,
or signs of inflammation. The tongue was of
normal size and papillated with midline
protrusion. Tonsils were not enlarged, the
palate was elevated symmetrically, and the
pharyngeal reflex was present.
-
- 2.5 Time line
- The patient underwent diagnostic
video-polysomnography on 29 March 2023, which
confirmed a diagnosis of severe OSA. This was
followed by an in-laboratory PAP titration on 18
April 2023. After initiating autoPAP therapy, a
follow-up evaluation was conducted on 27
November 2023. Although polysomnographic
parameters had improved, the patient reported
low adherence and treatment-related discomfort,
ultimately leading to discontinuation of therapy
(see Figure 1).
-
- 3 Diagnostic assessment
- 3.1 Laboratory findings
- Blood samples were obtained by venipuncture
after 12h of overnight fast. Laboratory tests
were made in the Hospital's Main Laboratory.
Laboratory testing revealed mild anemia with a
hemoglobin concentration of 13.5 g/dL and
elevated NT-proBNP 177.4 pg./mL. Other standard
blood tests were within normal limits:
electrolytes and inflammatory markers such as
C-reactive protein, leukocytes, and fibrinogen
were at normal levels.
-
- 3.2 Polysomnographic evaluation
- Two overnight vPSGs were performed at a
3-week interval. The first PSG examination was
performed to diagnose the patient's disorder;
the second PSG was applied with concomitant
positive airway pressure titration. PSG
recordings were analyzed by a physician, a
certified polysomnography specialist. A Nox-A1
device was used twice (Nox Medical, Reykjavik,
Iceland) for vPSG with audio recordings. PSG
data was recorded and analyzed thoroughly,
including analysis of audio and video
recordings, yawning episodes, sleep latency,
total sleep time, arousal index, sleep
efficiency (%); the ratio of N1, N2, N3, and REM
(rapid eye movement) sleep; analysis of
movements and sleep position; jaw muscles'
electromyography (EMG) recordings, respiratory
events recorded by a nasal pressure transducer,
and arterial oxygen saturation (SpOz). vPSG
recordings were scored with the standard
criteria of the American Academy of Sleep
Medicine (AASM) Task Force. Apneas were
diagnosed when there was a cessation of airflow
for ³10s, while hypopnea was confirmed when
there was a reduction in the amplitude of
breathing by ³30% for ³10s with a ³ 3%
desaturation or related to an arousal. SB events
were assessed based on EMG recordings from
bilateral masseter muscle activity supplemented
by audio and video. Bruxism episodes were
detected when the increase in the
electromyographic amplitude was at least twice
that of the background EMG.
-
- Electromyographic bursts within 3s were
considered to be part of the same episode.
Subsequently, the number of bruxism events per
hour of sleep was determined as the bruxism
episode index (BEl). According to the scoring of
rhythmic masticatory muscle activity (RMMA), a
phasic episode included three or more bursts
lasting 0.5-2s, and a tonic episode included a
single burst lasting longer than 2s. The
increase in electromyography had to have an
amplitude at least twice that of the background
electromyographic activity (12).
-
- 3.2.1 First polysomnographic examination
During the first diagnostic night, we performed
vPSG and observed 34 episodes of yawning during
sleep, which were linked to phasic bruxism
episodes. Some of them were present in clusters,
lasting from 4.6 s to a maximum of 31.2s, and
observed and heard in the video and audio
recordings. Yawning episodes were observed
before, in the middle, or at the end of phasic
bruxism episodes, mostly in N1 and N2 sleep
stages, followed by the transition to stage N1
or wake. The EMG recording of the yawning
episode had morphology of a tonic episode
directly linked with a phasic episode. We also
observed a few episodes of sleep-talking,
gasping, and loud yawning. The majority of
linked yawning-bruxing episodes were present at
the end of apneic/ hypopneic events followed by
desaturation. Moreover, PSG outcomes revealed 23
arousals/h, including both respiratory and
bruxism event-related arousals. BEl was
estimated at 11.7 events/h of sleep.
-
- 3.2.2 Polysomnographic examination with PAP
titration Yawning episodes were reduced but were
also observed during the second vPSG performed
with concomitant PAP titration, which was
conducted approximately 3 weeks after the first
examination. Before therapeutic intervention,
the technician fitted a nasal mask, which was
accepted by the patient, and set the therapeutic
pressure range to 4-17 cm H2O. Analyzing the
data, we have noticed the resolution of yawning
episodes, to the total number estimated n = 8,
1.3 episodes/h, occurring mainly in N1 and N2
sleep stages. We have also noticed AHI and BEl
reductions, according to the data revealed in
Table 1. Yawning episodes had the same
morphology assessed with EMG recording,
supplemented by videorecording. During the
interview, like after the first diagnostic PSG,
the patient was not aware of having episodes of
yawning or bruxing, and he also neglected
orofacial pain.
-
- 3.3 Therapeutic intervention
- After in-lab PAP titration, therapeutic
intervention included positive airway pressure
therapy (PAP), administered every night at the
patient's home. PAP therapy parameters included
a pressure range of 4-12 cm H2O, based on a
titration study. The patient was also given a
prescription for an individually fitted nasal
mask. The recommendations on PAP therapy
included using an autoPAP device for a minimum
of 4h/night, optimally for the whole night and
every night.
-
- 3.4 Follow-up and outcomes
- After several months, the patient was
admitted to the outpatient clinic to assess PAP
therapy results. According to the medical
interview, the tolerability and adherence to the
therapy were poor. The assessed period of PAP
therapy ranged from 26 April 2023 to 16 July
2023. After this time, the patient did not use
autoPAP. Device settings involved a minimum
pressure of 4 cm H2O, a maximum pressure of 16
cm H2O, and a median pressure of 7 cm H2O.
According to the therapy compliance, the patient
used the device on average for 3h 14 min per
night, for 66% of the nights. The estimated mean
AHI was 5 episodes/h, and the median leakage was
2.5 L/min. Despite satisfactory therapy results,
the patient was not planning to continue PAP in
the future. Although he was proposed to undergo
PSG hospitalization once again, he refused to do
it.
-
- 4 Discussion
- Our case report presents an unusual case of
yawning during sleep with a temporal, but not
causal, relationship with episodes of sleep
apnea and bruxism. It is worth noting that the
instrumental approach involved polysomnographic
examination supplemented by video- and audio
recordings performed twice in the same patient
in a small-time interval before and after the
therapeutic intervention with PAP.
-
- Although yawning during sleep is an unusual
presentation, alternative causes such as
nocturnal epileptic seizures, brainstem lesions,
or medication-related effects were considered
unlikely. The patient did not report daytime
confusion or any abnormal movements, and there
were no focal neurological symptoms in the
physical examination that would indicate central
nervous system pathology. Additionally, he was
not on medications known to influence
dopaminergic or cholinergic pathways. Given the
absence of neurological or pharmacological risk
factors, further neuroimaging was not deemed As
mentioned before, several theories on yawning
have been presented to date. The most crucial
concept of yawning's role assumes that this is a
thermoregulatory process leading to brain
cooling (13). For instance, Gallup et al.
reported two consecutive cases of women
reporting uncontrolled yawning attacks
accompanied by body temperature lowering (14).
The cooling mechanism was presented as the
circulatory dynamic of peripheral and cranial
blood flow. The blood flow variability was
previously linked with episodes of SB as a
result of cardiac activity controlled by the
autonomic nervous system. Thus, the yawning
episodes linked with SB episodes observed in the
current case may confirm this
temperature-lowering mechanism.
-
- Second, the arousal reflex of the brain (15)
against hypoxia may be linked with episodes of
sleep bruxism. Micro-arousals occurring during
sleep may be related to episodes of sleep
bruxism, mostly observed during sleep stage
transitions; thus, in our unusual case report,
concomitant yawning may also contribute to this
arousal mechanism, as the behavior is linked
with maintaining airway patency.
-
- This is in accordance with the theory of
Doelman and Rijken (16), indicating that yawning
may be a protective maneuver in preserving the
airway lumen and securing long-term oxygenation,
especially in individuals with a collapsible or
obstructing airway, such as in OSA patients.
This hypothesis may be further strengthened by
several observational studies performed on
patients undergoing surgeries. In these reports,
it was noted that upper airway collapse during
induction of anesthesia was associated with
increased yawning in more than half of the
patients (17, 18).
-
- The analysis of the first diagnostic PSG
found evidence for a higher number of yawning
episodes, intermitting apneic events, followed
by desaturation and its resolution under PAP
titration. Thus, the hypothesis on yawning as a
mechanism against hypoxia and arousal stimulus
is also a good starting point for discussion and
further research.
-
- Contagious yawning is also considered a
social behavior (3). Most of the theories
focused on empathic basis of contagious yawning
observed in humans and animals. Yawning
occurring during sleep, which is defined as
suspended consciousness of surroundings, leaves
this theory unverifiable, and several questions
on the socioemotional characteristics of yawning
remain unanswered.
-
- Neurochemical substrates of yawning were
previously determined: dopamine, serotonin,
acetylcholine, and oxytocin were previously
highlighted in the literature (4).
Hypodopaminergic activity was also previously
discussed in the literature as bruxism-provoking
factor (19). Hence, according to a similar
neurochemical basis, the current temporal
relationship between bruxing events and yawning
may suggest the need for future investigations
of dopaminergic activity in this context.
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- The main advantage of this case report are
that, according to the methodology section, the
instrumental approach to OSA diagnosis in that
case involved full-night PSG supplemented by
video-recording. Recordings allowed for to
diagnosis of the unusual presence of yawning
during sleep and obtained the most robust
results in conjunction with EEG and EMG
analysis. While a full polysomnographic
examination with EEG and EMG remains the gold
standard, in real-world settings, the use of
full-night PSG may be limited by cost, access,
and patient compliance. Alternative tools such
as ambulatory EMG and ECGbased monitoring have
gained attention as practical options for
assessing SB, particularly in patients with
comorbid conditions such as OSA, showing high
sensitivity and specificity (20). Nevertheless,
a recent study by Cid-Verdejo et al. (21)
compared the diagnostic accuracy of such
portable devices to PSG in patients with OSA and
highlighted their limitations in clinical
validation, especially in patients with moderate
and severe OSA. These findings show the need for
careful consideration of methodology for
accurately distinguishing true bruxism activity
from other motor phenomena during sleep.
-
- The main concern about the findings of the
current case report and patient perspective is
that the patient did not accept CPAP treatment
for a longer period. At the first evaluation,
the patient did not perceive the yawning
episodes during sleep and was unaware of their
occurrence. The OSA diagnosis was discussed, and
the patient agreed to the proposed treatment.
Intervention adherence and tolerability were
assessed during outpatient PAP control 7 months
after diagnosis. Despite satisfying results of
PAP titration, a well-fitted mask, and low
leakage, the patient reported discomfort with
the mask, perceived frequent air leaks, and oral
dryness. His adherence was suboptimal-he used
the device only 66% of nights and typically for
short periods. Despite extensive counseling
during the follow-up visit, he chose to
discontinue therapy and declined further
intervention. The patient did not attend
subsequent follow-up appointments. This may
support the observation that, beyond the
technical aspects of diagnosis, it is also
important to recognize the biopsychosocial
context of sleep-related phenomena such as SB.
Shared psychological and behavioral traits have
been observed in patients suffering from
overlapping conditions such as temporomandibular
myalgia and migraine, suggesting that central
sensitization, stress, and emotional regulation
may contribute to the manifestation and
persistence of orofacial pain and sleep
disturbances (22). Although our patient did not
report pain, the presence of bruxism and low
adherence to therapy raises important questions
about the underlying behavioral factors. In
summary, the current paper describes an unusual
case of concomitant behaviors: sleep bruxism and
yawning during sleep in patient with diagnosed
OSA. The presented case report leads to the
following conclusions: first, yawning episodes
were temporally linked with desaturation, as
were sleep bruxism events, suggesting a
secondary to hypoxia attribute of both
conditions. Second, the resolution of yawning
after PAP therapy strongly suggests a hypoxic
basis for yawning. Based on the literature, both
conditions are defined as complex issues
requiring future research.
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