Hypoxia And Sleep Disorders 

Introduction

Hypoxia is a condition where the body or a region of the body is deprived of adequate levels of oxygen.¹ Oxygen deprivation can be linked to various sleeping disorders that affect the timing, quality and amount of sleep you get.² Disorders such as these can have serious effects on your health and quality of life. This article will discuss the relationship between hypoxia and sleep disorders, exploring their impacts on health and well-being as well as the different management strategies available. Understanding this connection is essential as it allows us to take proactive steps to improve our sleep quality, health and overall quality of life.

Definition and causes of hypoxia

Hypoxia is defined as a reduction in the normal level of oxygen available to cells or tissues that arises when the oxygen demand exceeds the oxygen supply. There are four main types of hypoxia:¹

• Hypoxic hypoxia - this is the most common type of hypoxia where not enough oxygen enters the body due to low oxygen levels in the environment e.g high altitude or due to a medical condition where the lungs have a reduced ability to take in oxygen e.g chronic obstructive pulmonary disease, asthma
• Hypoxemic hypoxia - the blood is unable to carry sufficient levels of oxygen, commonly caused by carbon monoxide poisoning and anaemia. So, this means that even if there are sufficient levels of oxygen in the environment and the lungs are functioning perfectly the cells are unable to deliver oxygen. People with anaemia have insufficient red blood cells to deliver oxygen, while the red blood cells of people with carbon monoxide poisoning carry carbon monoxide rather than oxygen due to its higher affinity
• Stagnant hypoxia - there is insufficient blood flow to deliver oxygen to tissues and cells due to a problem with the circulatory system. This can be seen in patients with sickle cell anaemia, where red blood cells obstruct blood flow, people who have suffered from shock where there is a significant acute drop in blood flow and hyperthermia in cold conditions which causes vessels to constrict
• Histotoxic hypoxia - oxygen is delivered to cells but the cells are unable to use it. This is typically caused by poisoning, the most common form being cyanide poisoning which can be caused by inhaling industrial fumes

All types of hypoxia can affect different organs and systems, leading to a variety of symptoms. The overall effects of hypoxia depend on the severity, duration and underlying cause but the heart, lungs, immune system and brain among other things can be seriously affected.

Understanding sleep disorders

Sleeping disorders are any conditions that affect the quality, quantity and timing of sleep. They have a variety of causes and can manifest in numerous ways. The main effects are fatigue, irritability and low concentration levels, but they can also have serious long-term effects and have been closely associated with hypertension and heart attacks, strokes, diabetes, weakened immune systems and psychiatric disorders. Chronic sleeping disorders are estimated to affect over 70 million adults worldwide, some of which are caused by low oxygen levels and hypoxia₃. This is known as sleep-related hypoxia, a medical condition characterized by abnormally low levels of oxygen in the blood during sleep. This can result from various causes, including sleep apnoea, chronic obstructive pulmonary disease (COPD), or other respiratory disorders and is therefore most closely associated with hypoxic hypoxia which will be discussed in more detail.

Sleep apnoea

One of the most common sleep-related hypoxemia is sleep apnoea. Sleep apnoea is a sleeping disorder where your breathing stops and starts or becomes shallow while you sleep. This can lead to many different detrimental effects on daily functioning, mental health and even cardiovascular health. There are three types of sleep apnoea:

1. Obstructive sleep apnoea - this is the most common type of apnoea where the throat muscles excessively relax during sleep and block the airway. This happens on and off during sleep and is thought to affect over one billion adults worldwide⁴
2. Central sleep apnoea – occurs when the brain is not sending proper signals to the muscles involved in breathing. This is less common and often results in pauses in breathing
3. Complex or emergent sleep apnoea - individuals that exhibit a combination of both obstructive and central sleep apnoea. It is known as emergent as the central sleep apnoea becomes apparent only after treatment for the obstructive apnoea

Treatment

Treatments vary for each type of sleep apnoea,  but in general lifestyle modifications such as maintaining a healthy weight, avoiding alcohol and caffeine and getting regular physical activity can all be very effective, as is true for all sleeping disorders. Doctors may also recommend sleeping on the side to keep the airways open.⁴

Medical interventions include:⁴

• Breathing devices – provide constant pressure throughout the upper airways to keep them open during sleep e.g CPAP machine
• Oral devices – custom devices fitted into the mouth that keep the airways open usually prescribed if breathing devices can’t be tolerated
• Surgical implant - an upper chest/mouth implant that has recently been approved to help reposition the tongue and muscles that control the opening of the airways
• Surgery – to remove the tonsils from the mouth to open the airways and even jaw widening

Diagnosis

There are multiple tests to detect sleep apnea. A doctor will first evaluate your symptoms and sleep history, there they may refer you to a specialist sleep doctor who can conduct the following tests:⁴

• Nocturnal polysomnography – this test monitors heart and lung function, brain activity, blood flow and eye movement which will be conducted overnight. This helps to determine the severity of sleep apnoea
• Additional tests – this may be for related conditions and can include blood tests, x-rays, CT scans and specialized upper airways analysis

Other respiratory diseases

Although sleep apnoea is the most common hypoxic-related sleeping disorder, many other conditions can affect the sleep cycle. For example, various sleep-related hyperventilation disorders such as obesity hyperventilation can contribute to hypoxic conditions during sleeping. Interstitial lung disease that results in scarring and inflammation of the lung tissue can impair gaseous exchange, which can significantly alter breathing patterns, especially during sleeping. Other chronic diseases such as chronic obstructive pulmonary disease (COPD, congestive heart failure, or neuromuscular disorders can also impact sleep quality and contribute to the development or exacerbation of sleep-related symptoms.

It must be noted that sleep disorders can exacerbate each other without necessarily being the primary cause of each other. Where one condition worsens the other for example in chronic conditions such as COPD that causes disordered breathing and hypoxic conditions. Sleeping disorders and disturbances can exacerbate COPD symptoms.

Summary 

To conclude, understanding the complex relationship between hypoxia and sleep disorders is paramount for optimizing health outcomes. Hypoxia, characterized by low oxygen levels in the body, is closely linked to various sleep disturbances, including sleep apnea and respiratory diseases like COPD. By recognizing the interplay between these conditions, individuals can implement lifestyle changes and seek appropriate medical interventions to improve sleep quality, alleviate symptoms, and improve overall well-being.

FAQs

How is sleep apnoea diagnosed?

Sleep apnoea is typically diagnosed through a combination of symptom evaluation and sleep studies.

How does physical activity affect sleep disorders?

Regular physical activity can positively impact sleep by promoting better sleep quality and duration.

What should I do if I suspect I have sleep apnea or experience symptoms of breathing-related sleep disorders?

If you suspect you have sleep apnea or experience symptoms such as loud snoring, choking or gasping during sleep, daytime fatigue, or difficulty concentrating, it's important to see a doctor.

What are the potential risks of untreated breathing-related sleep disorders like sleep apnoea?

Untreated sleep apnoea can lead to serious health consequences, including an increased risk of cardiovascular diseases such as hypertension, heart attack, and stroke. It can also contribute to daytime drowsiness, impaired cognitive function, and accidents due to decreased alertness.

How does alcohol contribute to hypoxia-related sleeping disorders?

Alcohol can relax the muscles in the throat and tongue leading to increased airway collapse and obstruction during sleeping