Ever woken up in the middle of the night because of an uneasiness in breathing?
Sleep apnea is a medical condition where the breathing pauses during sleep due to a blocked or collapsing airway. As a result, the person wakes up to continue breathing.
Apart from disrupting a good night’s sleep, apnea causes several other health complications that are detrimental to an individual’s overall well-being. Some of these health issues include diabetes, hypertension, renal dysfunction, depression and obesity.
How does sleep apnea occur?
“The leading cause why people wake up in the middle of the night frequently or experience intermittent sleeping is because of sleep apnea,” Dr K Vinod, consultant pulmonologist, Veturi Polyclinic and Diagnostic Centre, Bengaluru, told Happiest Health.
In this type of disorder, the muscles at the back of the throat relax during sleep. This makes the body’s airway extremely narrow while breathing, decreasing the oxygen levels in the blood. We know that the brain needs continuous oxygen to function, so when the oxygen supply decreases, the body’s immediate response is to wake you up to open your airways. The process seems lengthy, but it happens so quickly that several people don’t even remember this when they wake up.
‘Increased prevalence of sleep-disordered breathing in adults’, a 2013 study by Paul E Peppard, Terry Young, Jodi H Barnet, Mari Palta, Erika W Hagena and Khin Mae Hla, found that 3 per cent of women and 10 per cent of men in the age group of 30-49 and 9 per cent of women and 17 per cent of men in the age group 50-70 are likely to have sleep apnea. Many researchers have said sleep apnea is more prevalent in men than women.
Types of sleep apnea
The three main forms of sleep apnea are:
1) Obstructive sleep apnea (OSA): This is the most common type. It occurs due to a functional obstruction in the mouth and throat. According to some studies, about 4-50 percent of the general population has OSA.
“OSA is often associated with obesity and metabolic syndrome. Metabolic syndrome is where a patient has high blood pressure, high blood sugar and high cholesterol levels,” said Dr K Vinod.
2) Central sleep apnea (CSA): In this type, breathing is inhibited due to upper airway obstruction, as seen in OSA. Instead, the cause of obstruction is neurological. In contrast with OSA, the body doesn’t try to breathe, so snoring is absent.
“Absence of snoring doesn’t mean that the person doesn’t have sleep apnea,” Dr Vinod says. In CSA, the brain and nervous system don’t consistently send a signal to breathe, and thus the person stops breathing.
A study titled ‘Effects of age on sleep apnea in men’ found that the prevalence of CSA was 1.7% in the middle-aged group and 12.1% in older adults.
3) Complex sleep apnea: The third and last type of sleep apnea combines OSA and CSA. There is an occurrence of periodic breathing (Cheyne-Stokes breathing patterns). “Cheyne-Stokes respiration is a specific form of periodic breathing (waxing and waning amplitude of flow or tidal volume) characterised by a crescendo-decrescendo pattern of respiration between central apneas or central hypopneas,” say Mohan Rudrappa, Pranav Modi and Pradeep C Bollu in a paper in the National Library of Medicine.
According to a 2013 research article, complex sleep apnea is “a form of sleep-disordered breathing in which central apneas persist or emerge when obstructive events have disappeared with continuous positive airway pressure (CPAP). Research has come a long way in developing a small, compact, and quiet CPAP machine compared to big ones. The design of the CPAP machine has been significantly streamlined to allow for better compliance regarding its use among individuals.
How it affects the body
“It is important to know that while just a disturbed sleep due to sleep apnea can cause chronic oxygen deprivation, more strain on the heart gives rise to hypertension, heart attacks and even strokes. Over time people can develop diabetes, kidney disease, obesity and even depression,” says Dr Shantanu Tandon, senior ENT surgeon, airway and sleep apnea specialist, Sakra World Hospital, Bengaluru.
Sleep apneas can affect the body in different ways:
1) Diabetes: ‘Sleep apnea and type 2 diabetes’, a 2018 study by Isao Muraki, Hiroo Wada and Takeshi Tanigawa, says, “OSA patients are more likely than non‐OSA populations to develop type 2 diabetes, while more than half of type 2 diabetes patients suffer from OSA.”
The study also said that both disorders are a risk for future cardiovascular disease, such as stroke, in which thrombosis is a crucial factor in pathogenesis.
2) Hypertension: Hypertension is the elevation of arterial blood pressure above a particular value. It can either be systolic or diastolic.
A 2014 review found that OSA is related to an increased risk of resistant hypertension. Mild, moderate and severe OSA is associated with essential hypertension. The associations are stronger among male OSA patients.
3) Renal dysfunction: “Renal dysfunction can occur due to direct effects of hypoxia in OSA or due to hypoxia-induced oxidative stress,” Dr K Vinod says. Studies have also indicated that OSA can lead to a rapid increase rate of kidney function decline. However, there is also evidence that the presence of end-stage renal disease can lead to worsening sleep apnea — indicating a bidirectional relation between sleep apnea and renal dysfunction.
4) Depression: Apart from physical disorders, sleep apnea can affect psychological health too. “Many symptoms of depression and obstructive sleep apnea overlap, causing under-diagnosis of obstructive sleep apnea (OSA) in depressed patients. OSA patients can present with major depressive symptoms,” according to a study by Shazia Jehan, Evan Auguste and Samy I McFarlane titled ‘Depression, Obstructive Sleep Apnea and Psychosocial Health’.
5) Obesity: Increased body weight or obesity has long been associated with sleep apnea, specifically OSA. According to a study, significant sleep apnea is present in 40 per cent of obese individuals and 70 per cent of individuals with OSA are obese. A history of weight gain is considered a symptom of developing OSA. Just like renal dysfunction and hypertension, obesity and sleep apnea are interrelated. Among other factors like lifestyle variations, weight gain in OSA may also be related to endocrine dysregulation.
While researchers are at work developing models for the treatment of sleep apnea other than wearing face masks, the most advisable therapy by doctors is the CPAP (continuous positive airway pressure). In this, people breathe in a controlled pressure of air through a face mask which is attached to a hose and beside a pump.
But when people don’t know why exactly they suffer from disturbed sleep, it is best to reach out to a sleep specialist or a doctor.