Sleep apnoea occurs when the walls of the throat come together during sleep, blocking off the upper airway. Breathing stops for a period of time which can be from about a few seconds but can be as long as one minute. This sends a signal to the brain that there is a drop in oxygen levels and one wakes up, snorts and gasps, and then goes back to sleep.

Many times, the person who is suffering from sleep apnoea does not know that they are waking up in the night. Moreover, this is usually a frequent occurrence and happens many times at night. This is why people suffering from sleep apnoea wake up tired and get very sleepy during the day, feel tired and lack concentration.

Unfortunately sleep apnoea can also have serious complications as it is a risk factor for highly serious conditions including high blood pressure, insulin resistance, systemic inflammation, visceral fat deposition, dyslipidemia and an increased risk of heart attack and stroke.

For some time it was believed that sleep was important primarily for restoration of brain functions. However various studies have shown that sleep affects metabolic and endocrine regulation, immune functions and cardiovascular variables. It has been shown that sleep deprivation of 60 hours is associated with decreased insulin sensitivity. A recent study has also shown that restricting sleep to four hours per night for six nights in young, healthy individuals lowers glucose tolerance. Also, the same group reported that short sleepers, based on self-report, showed significant impairment of glucose metabolism compared with controls.

This evidence shows that chronic sleep loss could contribute to conditions such as diabetes and hypertension.

Sleep apnoea should not be confused with people who snore, as the latter do not suffer from daytime sleepiness or other symptoms.

There are various degrees of severity of this condition, ranging from normal, which is less than five interruptions an hour, to mild, which is between five and 15 interruptions an hour, and on to moderate, which is between 15 and 30 interruptions an hour, and severe, which is over 30 interruptions an hour.

The degree of symptoms and possible complications increase as the severity increases.

A 10 per cent weight loss can result in a more than 20 per cent improvement in obstructive sleep apnoea severity

There are various factors which contribute to obstructive sleep apnoea. Obesity is considered a major risk factor for the development and progression of obstructive sleep apnoea. In fact, obstructive sleep apnoea in obese or severely obese patients is nearly twice that of adults with a normal weight. Furthermore, patients with mild obstructive sleep apnoea who gain 10 per cent of their baseline weight are at a six fold increased risk of further progression of obstructive sleep apnoea.

Moreover, the higher prevalence of obstructive sleep apnoea in obese people is not limited to adults as recent studies have shown that obese children have a 46 per cent prevalence of obstructive sleep apnoea when compared with children seen in a general paediatric clinic (33 per cent).

The good news is that a loss of around five to 10kg may be enough to dramatically reduce the severity of the disorder. In fact a 10 per cent weight loss can result in a more than 20 per cent improvement in obstructive sleep apnoea severity. These findings highlight the need to develop screening and prevention for obesity even as early as in childhood.

Alcohol consumption especially in the evening relaxes the throat muscles and hampers the brain’s reaction to sleep disordered breathing, hence leading to increased risk of sleep apnoea. Other factors which can lead to this condition include certain illnesses, like an enlarged goitre and large tonsils. Nasal congestion and obstruction can also lead to this condition as do some medicines such as sedatives and sleeping medication.

Treatment for sleep apnoea relies on changes to lifestyle, including losing weight and cutting down on alcohol. Any contributing medical condition, such as low production of thyroid hormone, also needs to be corrected.

The same applies to any surgical conditions such as large tonsils. The most effective treatment available is a mask worn at night that keeps the back of the throat open by forcing air through the nose. This is called nasal continuous positive airway pressure. However, some people with sleep apnoea find the mask difficult to tolerate. It is strongly recommended to speak to your family doctor if you are suffering from these symptoms to take immediate action to avoid possible complications.

Symptoms of sleep apnoea

• Daytime sleepiness, fatigue and tiredness
• Poor concentration
• Frequent urination in night
• Irritability and mood changes
• Impotence and reduced sex drive

Other sleep disorders

Insomnia

Symptoms: Difficulty falling and staying asleep, waking up early, feeling tired and irritable, finding it hard to concentrate.

May lead to: Decreased quality of life, sleepiness during the day, depression.

Restless leg syndrome

Symptoms: Tingling, pins and needles, prickling, pulling or crawling feelings in the legs, periodic limb movements.

May lead to: Anxiety, stress and high risk of traffic accidents or other accidents if operating heavy machinery at work.

Narcolepsy

Symptoms: Excessive daytime sleepiness, hallucination, sleep paralysis and cataplexy, which is the sudden loss of muscle tone that leads to weakness.

May lead to: Proneness to accidents, poor attention span, headaches and obesity.

Dr Charmaine Gauci is director, Health Promotion and Disease Pre-vention Directorate and consultant, Public Health Medicine.