Medical and dental conditions related to SRBD
Research during the past decade has confirmed that sleep disorders adversely affect various physiological systems, including cardiovascular, endocrine, metabolic, nervous, and immune.
Therefore, there has been an awareness that sleep disorders may well increase the risk for health-related consequences. While cardiovascular disease has been found to be one of the more significant consequences of Sleep Related Breathing Disorder (SRBD), the risk for other serious health problems has also been established.
Health consequences associated with SRBD
An increasing frequency of metabolic syndrome is linked with SRBD. Metabolic syndrome is the term for a group of risk factors that are associated with specific health issues, including but not limited to cardiovascular disease, stroke and diabetes. In one research study, the presence of metabolic syndrome was found to be almost 40% greater in SRBD subjects than in control subjects.
The criteria by which metabolic syndrome is diagnosed is that an individual has a minimum of three of the five following metabolic risk factors:
- increased girth of the waist or having a gut with an increased body mass index (BMI)
- increased blood pressure
- increased blood levels of triglycerides
- decreased blood levels of high-density lipoprotein (HDL) cholesterol
- impaired fasting glucose
The occurrence of diabetes and obesity in the United States is increasing. The link of these risk factors to metabolic syndrome lends to the estimate of almost 50 million adults with this syndrome. In conjunction with , obesity is associated with other health problems such as increased insulin resistance, increased levels of cholesterol and triglycerides, and a variety of other health consequences, primarily related to cardiovascular disease.
The most widely acknowledged association with SRBD and even just sleep loss or restriction relates to the presence of obesity. However, SRBD does not have to be present for obesity to occur. Sleep restriction or a decrease in adequate hours of sleep can also lead to the obesity. The sleep loss and obesity association are not exclusive to adults. Obesity in children and adolescents is a growing concern and seems to be also be related to a lack of adequate number of hours of sleep.
It is vital to recognize that not all patients with SRBD are obese. Even the non-obese are at risk for health problems, associated with short sleep duration. An increase in abdominal girth or central (visceral) size is the one common finding that most often indicated SRBD as increasing the risk for health-related consequences.
Since the early 1990’s research has recognized that an individual with SRBD is at an increased risk for elevated blood pressure or hypertension. One research study looked at the incidence of hypertension in obstructive sleep apnea (OSA) patients independent of obesity, and it demonstrated the following:
- the incidence of elevated blood pressure existed in 20-70% of OSA patients
- nocturnal SRBD was more closely related to elevated blood pressure
- significant OSA was found in 30-40% of hypertensive patients
Awakenings/arousals from sleep are also a factor in the elevation of blood pressure. These repeated arousals are associated with an increase in blood pressure during the day, and they appear to be related to an increase in sympathetic activity or tone that occurred during sleep and resulted in a rise in daytime blood pressure. The landmark Sleep Heart Health Study further established an association between SRBD and hypertension.
Snoring alone can also give rise to an elevation in blood pressure. A study demonstrated that snoring without any significant hypopnea or apnea can result in hypertension, but the risk is lower. Another study showed that SRBD and the risk for hypertension were larger in young males than in males over age 60. Given the fact that snoring over time can lead to OSA, this should not be taken lightly.
The development of cardiovascular disease takes on a variety of related circumstances, all of which have been found to be predominant in the presence of SRBD. Studies may vary on the degree of risk, but it is commonly agreed upon that SRBD is a significant factor in the presentation of cardiovascular disease.
Various arrhythmias have been documented during episodes of OSA, and these arrhytmias are resolved with continuous positive airway pressure therapy. In addition, bradycardia, and tachycardia have been implicated as associated with OSA. Hypoxia’s main outcome is Bradycardia is the main outcome in hypoxia (deficiency in the amount of oxygen reaching the tissues). Arrhythmia appears to be associated with oxygen desaturation, is common in patients with coronary heart disease, and appears to resolve with the management of the apnea.
There is an association between the presence of atrial fibrillation and sleep apnea. The odds for the association of atrial fibrillation with OSA was found to be 2.19. All the patients monitored were similar, particularly as it relates to the presence of hypertension, diabetes, and congestive heart failure (CHF).
Atherosclerosis, endothelial dysfunction, and coronary heart disease
Obstructive Sleep Apnea (OSA) and the presence of coronary artery disease is noteworthy. A study found that in a population of patients who had symptomatic angina diagnosed with angiography, 30.5% had OSA. This group had a higher apnea-hypopnea index and more of a tendency to be overweight or obese.
The potential for atherosclerosis is also greater among OSA patients. Although these patients may be free of signs and symptoms of cardiovascular disease, coronary heart disease and atherosclerosis were discovered to be significantly as the degree of OSA worsened. The significance of this is serious if one considers that only 12.5% of a control group had signs of coronary heart disease while mild OSA patients demonstrated a 42% incidence and moderate to severe patients had an 80% incidence of disease in multiple vessels. Sleeping less than 7 hours a night or more than 8 hours may increase the risk for coronary heart disease.
Endothelial dysfunction can also be associated with OSA. These can be subsequent relaxation in the vascular structure as well as atherosclerotic changes and cardiovascular disease, and endothelial injury at a tissue level leads to atherogenesis (a disorder of the artery wall that involves: adhesion of monocytes and lymphocytes to the endothelial cell surface). The progression of atherosclerosis may be related to apnea events that alter inflammatory mediators and metabolic factors, which can result in hypertension. These related events lead to atherosclerosis and cardiovascular disease.
A current research study has established that snoring alone may put patients at risk for atherosclerosis of the carotid artery. The proposed mechanism involves vibrations in the pharyngeal airway that are in close proximity to the artery, and these vibrations may cause endothelial damage that results in inflammation and thereby promotes changes that may lead to atherosclerosis. The prevalence of the atherosclerosis worsened in direct proportion to the degree of snoring, and the prevalence ranged from 20% in mild snorers to 64% in heavy snorers.
Congestive Heart Failure
The association of cardiovascular disease and sleep apnea is well known. CHF has been found to be prevalent in patients mainly with central sleep apnea (CSA). The recurring respiratory events are associated with sleep disruption, arousals, hypercapnia and hypoxia. It appears that a large percentage of patients with heart failure when screened for SRBD tested positive. Furthermore, there is often times a relation between Cheyne-Stokes respiration and Congestive Heart Failure (CHF) that is present in CSA patients.
Interestingly, the use of an oral appliance (OA) can beneficially impact CHF. In these studies, the focus in determining the effect of OA’s was based on the measurement of brain natriuretic peptide (BNP), which has been found to be elevated in OSA. This increase is linked to left ventricular pressure and volume levels. In patients with CHF, the BNP levels rise and are associated with sudden death, and it may predict morbidity and mortality.
Cerebrovascular function and stroke
Stroke is the third leading cause of death and long-term disability. The incidence of cerebrovascular disease and stroke is related to SRBD and it is independent of other recognized risk factors for stroke. The risk for stroke associated with OSA is also independent of hypertension, but the existence of hypertension further increases the risk.
The mechanism is related to a decrease in cerebral perfusion and increased coagulation. There is an increase incidence of sudden death during sleep. In addition, after stroke, there is an increase in the prevalence of OSA, which affects the ability of the patient to rehabilitate and recover following the stroke.
Triglycerides and cholesterol
HDL, or the good cholesterol, functions as both an antioxidant and an antiatherogenic. HDL dysfunction has been found to be present in OSA patients. This association is related to oxidative stress, which is present in patients with coronary heart disease. Lower levels of HDL have also been linked to issues with short- term memory deficits. Difficulty with memory has also been linked to OSA as one of the common symptoms.
Diabetes Type 2
2 Diabetes is linked to SRBD such as snoring and OSA. In fact, snoring alone has been shown to be an independent risk factor for this type of diabetes. The impact of snoring and OSA, by virtue of upper airway obstruction may lead to oxygen desaturation that in turn may cause a rise in the level of cortisol and catecholamines. The outcome of this cascade can be an increase in insulin resistance, which is a precursor to diabetes. The landmark Sleep Heart Health Study demonstrated that hypoxia during sleep resulted in glucose intolerance which was independent of age, sex, the size of the waist or BMI. Additional studies have also shown that SRBD, regardless of obesity, may serve as a contributing factor to diabetes through its association with glucose and insulin metabolism.
Sleep disruption has also been shown to be common among those with type 2 diabetes. Three main factors were discovered that are related to sleep disruption: pain, obesity, and an increase in the need to use the bathroom during the night. One-third of those who have type 2 diabetes experience sleep problems. In addition, the severity of the diabetes is directly related to sleep problems. Furthermore, the severity of the diabetes is directly related to the sleep disruption.
Sleep restrictions and excessive sleep are other issues that may impact the risk for diabetes. Getting between 7 and 8 hours of sleep a night is optimum Less than 6-7 and over 8-9 hours can lead to an increased risk for diabetes. Although, After adjusting for BMI (where the tendency for being overweight or obese was corrected) the increased risk for diabetes became modest.
Gastroesophageal reflux disease
Gastroesophageal reflux disease (GERD) is estimated in the United States to be experienced daily by 7% of the adult population and weekly by 70% Historically, there has been a slow acknowledgement of sleep-related GERD as well as its impact of daily function .
Many people who have SRBD also may complain of may have been diagnosed with GERD. The occurrence of GERD is much higher in patients with OSA as compared to the general population. This is a condition that is associated with the relaxation of the phreno-esophageal sphincter where the esophagus enters the stomach, and it is oftentimes associated with obesity and diabetes.
GERD may be more prevalent in SRBD because of the following:
- Negative pressure in the airway is associated with narrowing of the airway during inspiration, which also impacts the esophagus. This negative inspiratory (intrathoracic) pressure generate during apnea is not selective to the airway, and thus the esophagus is also affected.During expiration, the negative pressure is released , and the potential for reflux to occur is greater.
- Lying in the prone position where the effects of gravity are negated increased the risk for reflux. For this reason, many people with GERD sleep in an elevated position.
Common symptoms of gastroesophageal reflux disease:
- Nocturnal awakenings
- Noncardiac chest pain
- Acidic damage to teeth
- Laryngopharyngitis (Inflammation of the larynx and the pharynx)
- Bronchial asthma
- Chronic bronchitis
- Pulmonary aspiration
- Chronic cough
GERD, particularly when present at night along with OSA , was discovered to be a cause of sleep disturbance. The presence of GERD-type symptoms is likewise associated with awakenings from sleep. It has been estimated that the symptoms of GERD can cause awakenings in 58.6% of these patients. Other symptoms associated with these awakenings are difficulty in initiating sleep and experiencing nightmares. It was also shown that patients with GERD had more symptoms of excessive daytime sleepiness (EDS) as well.
The presence of asthma, along with other respiratory conditions, may be associated with SRBD. In the general population, the prevalence of asthma is 5%. The coexistence of asthma and OSA is not well documented, although from a clinical perspective, many people who have SRBD also have asthma.
The one significant association that exists between asthma and SRBD is between asthma and GERD, the common denominator being the presence of inflammation. This same inflammatory condition has also been implicated in the advancement of OSA. Nocturnal GERD associated with OSA can lead to the introduction of asthma. The presence of obesity and airway obstruction are also common findings. The role of reflux in the precipitation of asthma has been linked to an elevation in BMI. As the BMI increases and obesity is more prevalent, the incidence of asthma also increases.
The link between Alzheimer’s disease and OSA is becoming more apparent. The mutual finding at this time is the presence of a genotypic marker known as apolipoprotein (APOE4), which is a risk factor for Alzheimer’s and cardiovascular disease. For those who carry this marker, there seems to be some complex interaction with brain pathology, OSA and cardiovascular disease. One study demonstrated the relationship that exists between this genotype and OSA.
OSA and the association of hypoxia in the elderly may be linked to mental deterioration that is associated with dementia. Additional research will be needed to confirm this association, but the proper management of SRBD may be a noteworthy factor. It is also conceivable that the proper management of hypertension, diabetes, or elevated cholesterol is important because all three of which are commonly occurring conditions in SRBD.
In the early part of the 2000s, the association of cardiovascular disease, elevated blood pressure and other health issues as a consequence of SRBD (particularly snoring and OSA) were thought to be connected to the presence of respiratory events during sleep. Also, the significance of hypoxia associated with the drop-in oxygen saturation was also a thought as was the impact on the sympathetic nervous system.
The hypoxia that can occur during SRBD can lead to a rise in the incidence of oxidative stress that in turn will lead to an increase on free radical production. This complex group of events is directly linked to the arrangement of hypertension, cardiovascular disease and endothelial cell damage. Furthermore, there is a lessened level of nitric oxide, which is an agent that caused vascular relaxation (dilation) that is by itself a free radical. Levels of nitric oxide are impacted by hypoxia, particularly when hypoxia is chronic.
Also, the presentation of atherosclerosis may be an outcome of the modification of LDL (the bad cholesterol that contributes to the clogging of arteries) by oxidation that results I injury to endothelial cells as well as the underlying smooth muscle cells.
One animal experiment found that residual sleepiness (which may be an issue with some OSA patients despite adequate management of the apnea) may be related to long-term intermittent hypoxia associated with oxidative stress that results in neuronal injury of wake-promoting areas of the brain. It is not known as to what degree the injury occurs. More research is needed to clear up this issue. Nevertheless, the underlying theme should be that the sooner the SRBD is recognized and treated, the better off the outcome may be.
PAIN AND SLEEP
Pain and painful conditions can be augmented by lack of sleep or by sleep disorders. Likewise, pain can lead to a loss of sleep, poor quality of sleep and a reduction in a suitable number of hours of sleep that only continues to preserve the pain cycle. Therefore, the improvement in sleep can in and of itself lead to pain reduction. This realization (despite the recognition of the relationship of these two conditions) has not had noteworthy attention until recently.
Research shows that chronic pain can be present in 11 to 29% of the adult population, and that 50 to 90% of these individuals can indicate that their sleepiness is adversely affected by their pain.
There are a number of painful conditions that the dentist will encounter. Thus, it is imperative that the loss/lack of sleep be considered in the overall management plan for the painful condition. Also, it is essential that an understanding of the relationship between pain and its relationship to the sleep state be considered when planning for the management of each situation and condition.
Many times, the management of bruxism is predicated on tooth wear of coexisting conditions such as headache, temporomandibular disorders or myofascial pain. It is significant for the dentist to understand that bruxism is a medically described sleep disorder.
Sleep bruxism, also known as rhythmic masticatory muscle activity (RMMA), has been shown to be part of a sleep arousal response that is associated with the central nervous system and specifically the dopamine system. Other factors have been considered such as stress, psychological factors and personality traits, although they are now believed to play only a minor role.
Sleep bruxism may be classified as either a comparison of awake time versus sleep time.
|Awake time bruxers||Sleep time bruxers|
|Tooth clenching||Tooth grinding|
|Tooth tapping||Jaw muscle contractions Phasic (rhythmic)|
|Jaw bracing (no tooth contact)||Tonic (sustained)|
Lastly, teeth occlusion has in the past been considered to be a factor in bruxism but is now viewed as playing only a limited role.
Sleep bruxism predominantly occurs during nonrapid eye movement (NREM) stage 2 and rapid eye movement (REM) sleep. Research points to that sleep bruxism appears to be related to microarousals.
In addition, the sleep bruxism may be more prevalent when the patient sleeps on their back. Sleeping on the back is the worst position for
Snoring and Obstructive Sleep Apnea (OSA) have an increased risk in patients with sleep bruxism. It has been determined that the odds ratio for snoring, OSA and EDS is 1.8 % ,1.4%, and 1.3% respectively.
Of particular interest to the dentist are patients with an orofacial pain condition. As with pain in general, these conditions are frequently associated with some type of sleep disruption. Similar to other types of painful conditions, it may be difficult to determine which came first the pain or the sleep problem.
Irrespective of the type of orofacial pain complaint, focusing on the sleep issues is most often helpful in managing the pain problem.
Many times, the presence of temporomandibular disorder (TMD) is associated with muscle pain and or sleep bruxism. In 2001 a National Heart, Lung, and Blood Institute workshop noted that patients with TMD were also at risk for cardiovascular and sleep related consequences. The findings of this reserach showed that patients with TMD were similarly at risk for and predisposed to cardiovascular disease, including related conditions such as heart failure, hypertension and stroke. The study also concluded that additional research is needed to actually understand the relationship that appears to exist amongst these conditions. Evidence suggests this relationship may be related to interactions in the central nervous system. These interactions may impact the presentation of TMD as well as alterations in sleep architecture.
The pain attacks are often unilateral, and they are described as sharp or electric-like and usually brief and unpredictable. The interesting fact related to this pain and sleep relationship is that the attacks do not occur during sleep.
Sleep loss and pain
Of interest is the finding that sleep loss, specifically 4 hours and REM-type sleep, is related with Hyperalgesia the following day. There is a bidirectional relationship between the loss of sleep and pain. That is to say, the loss of sleep impacts pain levels and pain levels can reduce the amount of sleep.
One research study demonstrated that sleep is pain-relieving in nature. In patients with osteoarthritis, improvement of sleep latency and sleep efficiency was analgesic when compared to control subjects.
|Type of Headache||Relevant findings|
|Migraine Headaches||May occur at night with stages 3 an 4 NREM sleep
Occurs in 54% of narcoleptics
May be provoked by sleep
Common to sleep for relief ( related to serotonin)
Responds best to proper sleep hygiene
|Cluster headache||Occurs predominantly at night between 9 and 10 p.m.
Linked to REM sleep
Linked to sleeping late
|Chronic Paroxsymal Hemicrania (CPH)||May be greater at night
May wake the patient
Considered variant of cluster
Linked to REM sleep
Responds to indomethacin (indocin)
|Tension Type Headache (headaches)||Becomes less with increased activity-disappears when awake and active
Successful treatment of sleep apnea decreases the headaches
Occurs with increased bruxism, alcohol, sinus inflammation
|Hypnic Headache||Prevalent in older people
Rem sleep-related disorder
Appears with dreams
Duration of 1-2 hours
No migraines symptoms
Responds to aspirin
Prophylactic therapy: lithium, caffeine, indocin