'Apnoea' means not breathing. Sleep apnoea is the inability to breathe whilst asleep. The frequent attacks of sleep apnoea disturb sleep profoundly. Because sufferers do not have enough sleep at night, they feel tired all day and have no energy to do anything. They are unable to concentrate at work, and lose interest in sex and other things they enjoyed before. This is another common cause of excessive daytime sleepiness, and is now studied extensively in sleep laboratories. As a result, this condition is now believed to be more common than was previously believed. It is estimated that over 1 per cent of the adult population is suffering from sleep apnoea.
Sleep apnoea becomes more frequent as we grow older. The typical sufferer is a man over forty years of age who is grossly overweight and has high blood pressure. His sleeping partner invariably complains that he is snoring every night. A keen observer may be able to report that the sufferer snores very heavily, then wakes himself up, takes a few deep breaths, and falls back into snoring again. This may happen many times throughout the night In fact people suffering from sleep apnoea do not have any real sleep. They keep waking up throughout the night. However, in the morning, they may not remember that they have been waking up frequently, but somehow have the feeling that they have not slept. They also fall asleep very easily in the daytime, at the most inappropriate times. Many road accidents involve people who have sleep apnoea.
This condition is caused by obesity; in particular, the accumulation of fat around the throat. During sleep, air is sucked into the lungs, creating negative pressure around the surroundings of the throat and the tongue, which leads to a reduction in the diameter of the throat. This reduces air flow into the lungs. In normal people this reduction in the diameter of the throat is minimal, and may create only a snoring sound. Snoring results from the vibration of the palate, which is the roof of the mouth, as air is blowing across it. The flute and other woodwind instruments work on the same principle. In some obese people the air passage is narrowed far more than in normal people because of the accumulation of fat around the throat. This causes an even greater reduction in the flow of air to the lungs and results in obstructive sleep apnoea.
The condition is made even more severe during REM sleep. In REM sleep the muscles of the body are almost paralysed. Hence the muscles in the throat become flaccid and the diameter of the opening is further reduced. Because there is a reduced air flow into the lungs the person is virtually suffocating; this subsequently reduces the amount of oxygen circulating in the brain.
For normal people, the blood oxygen level during sleep stays above 90 per cent, but for sufferers of sleep apnoea this may go down to 40 per cent at times. Whenever the brain is deprived of oxygen, the body is signalled that all is not well, and the person wakes up immediately. After taking a few deep breaths, the brain regains its oxygen supply and the body feels that all is well. The person falls back into sleep, and snores again. Further cycles of waking and snoring then follow. This snoring/waking cycle repeats itself many times throughout the night. Normal people may also have occasional attacks of apnoea, but less than four times in one hour. People with sleep apnoea have as many as 30 attacks in one hour, and each attack of apnoea may last as long as three minutes. Because there is not enough air going into the lungs, and consequently less oxygen is circulating in the blood, these people may suffer from high blood pressure and irregular heart beats. It is thought that many heart attacks and strokes are triggered during these attacks of sleep apnoea.
Professor Colin Sullivan at the University of Sydney devised a nasal mask which can be worn during sleep. Air is pumped through the mask to ventilate the lungs by an electric pump. This device is now available commercially and is called continuous positive airway pressure, commonly known as 'CPAP', which is pronounced as 'see-pap'. Besides this, there are other ways of helping sufferers of sleep apnoea. Weight reduction in the obese is very important, as this is sometimes the main cause of sleep apnoea. Tablets can also be given to reduce the time spent in REM sleep, as sleep apnoea is worse during REM sleep. Some sufferers may consume an excessive amount of alcohol or may be heavy smokers. Giving up drinking and smoking will definitely help. Plastic surgery of the soft palate and the oral cavity is sometimes very successful.