The word “apnoea” (apnoea) literally means “without breath” in Greek.
There are three types of sleep apnoea: obstructive, central, and mixed; of the three, obstructive is by far the most common. Despite the causative differences of each type, people with untreated sleep apnoea stop breathing repeatedly during their sleep. This may happen hundreds of times during the night and can often last for a minute or longer.
Obstructive sleep apnoea (OSA) is caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses and closes during sleep. In central sleep apnoea, the airway is not blocked but the brain fails to signal the muscles to breathe. Mixed apnoea is a combination of the two. With each apnoea event, the brain briefly arouses people with sleep apnoea in order for them to resume breathing, but consequently sleep is extremely fragmented and of poor quality.
When obstructive sleep apnoea occurs, the tongue is sucked against the back of the throat. This blocks the upper airway and airflow stops. When the oxygen level in the brain becomes low enough the sleeper partially awakens, the obstruction in the throat clears and the flow of air starts again. This usually occurs with a loud gasp. People with obstructive sleep apnoea suffer from disrupted sleep and low blood oxygen levels.
The cycle of apnoea:
- The sufferer falls asleep.
- Muscle tone in their body relaxes.
- Their airway narrows and/or collapses, causing breathing to be difficult or impossible. The collapse of their airway may cause loud snoring, snorts, pauses in airflow, and laboured breathing.
- Their oxygen levels begin to fall.
- They continue to struggle for breath, sometimes for up to a minute.
- Their heart rate falls below normal, and there is decreased oxygenated blood to pump through their body.
- Their brain senses low oxygen/high carbon dioxide levels and releases jolt of adrenaline in an attempt to awaken their brain and body and prevent suffocation.
- The sufferer awakens briefly and takes five or six large breaths breathing in oxygen and blowing off excess carbon dioxide (CO2). The sufferer typically does not remember arousal but often repositions him or herself on the bed.
- Their heart rate speeds up in response to the rush of adrenaline and is now pumping above normal heart rate.
- Their oxygen/carbon dioxide levels return to near normal and their brain allows them to resume sleeping.
- The sufferer falls asleep and the cycle repeats.
Difficult To Detect
It is not unusual for an apnoeic patient to have over one hundred arousals per night, although he or she most likely will not remember any of them. This makes apnoea suffers, especially those who live alone or sleep in bedrooms separate from their partners (a common result of their intense snoring and loud gasping), vulnerable to not having their condition diagnosed for many years, if ever.
Severity of sleep apnoea is measured by three variables, blood oxygen level and the presence of daytime sleepiness and the number of apnoeic episodes per hour-also known as an Apnoea/Hypopnea Index (AHI).
An AHI of 5-15/hr is considered mild sleep apnoea.
An AHI of 16-30/hr is considered moderate sleep apnoea.
An AHI of +30/hr is considered severe sleep apnoea.
Signs and Symptoms of OSA
OSA occurs in 24% of men and 9% of women in the middle-aged workforce between the ages of 30-60, which is approximately as often as adult diabetes. Sleep apnoea can affect anyone at any age, even children. Due to a lack of public awareness, the vast majority of sufferers remain undiagnosed and therefore untreated despite the fact that the disorder can have serious medical consequences.
The signs and symptoms of OSA result from disruptions of normal sleep patterns. Frequent arousals and the inability to achieve or maintain deeper stages of sleep can lead to excessive daytime sleepiness, automobile accidents, decreased memory and depression. Additional physical signs include loud snoring and witnessed apnoeic episodes. Any of these may be a sign or symptom of OSA.
Although patients rarely complain of them, frequent awakenings due to obstruction do occur. Excessive daytime sleepiness may be mild or severe depending on the severity of the obstruction. Some patients suffering from OSA fall asleep in an unstimulating environment, such as while reading in a quiet room. Others may fall asleep in a stimulating environment, such as during business meetings or eating. Other symptoms of OSA include morning headaches and frequent urination during the night. Patients with OSA often complain of waking up feeling like they have not slept at all. They often actually feel worse after taking a nap than they did before napping.
The so-called drowsy driver syndrome, which a growing number of law enforcement authorities believe to be responsible for many automobile accidents, may result from OSA. Undoubtedly, OSA causes some drivers to fall asleep at the wheel or to suffer from a lack of alertness due to sleep deprivation. Decreased alertness places a person at risk in a variety of potentially hazardous situations. If you suffer from excessive daytime sleepiness SomnoMed highly recommends that you do not drive a vehicle or operate dangerous equipment until your condition is effectively treated.
The Consequences of OSA
The most obvious complication arising from OSA is diminished quality of life brought on by chronic sleep deprivation and the symptoms described above. Cardiovascular disease and stroke are being evaluated to define the exact nature of their connection to OSA. Some linkage between OSA and coronary artery disease and stroke has been demonstrated.
If left untreated, sleep apnoea has been linked to hypertension (high blood pressure), cardiovascular disease, memory problems, weight gain, impotency, and headaches. Sleep apnoea may also be responsible for many instances of job impairment and motor vehicle crashes. In addition to these problems, sleep apnoea wreaks havoc with the quality of the sufferer’s sleep because they are only able to sleep in small bursts. Fortunately, sleep apnoea can be diagnosed and treated, and several treatment options exist.