Obstructive sleep apnoea (OSA) is caused by the muscles in the back of your throat relaxing during sleep. These muscles support your tongue, tonsils and soft palate (a muscle at the back of the throat used in speech).
Once the muscles relax, the airway in your throat can narrow or become totally blocked. This interrupts the oxygen supply to your body which triggers your brain to pull you out of deep sleep so that your airway can be reopened and you can breathe normally.
As you need to have a certain amount of deep sleep in order for both your body and your mind to be fully refreshed, only having limited episodes of deep sleep will lead to you feeling very tired the next day.
Most adults require at least eight hours of sleep to function at their best and 50% of that time should be spent in the deepest phase of sleep.
Known risk factors for OSA
The known risk factors for OSA are outlined below.
- Obesity - the more obese you are, the higher the risk. For example, a 10% increase in your weight will lead to a six-fold increase in your risk of developing OSA.
- Being male - the reasons why OSA is more common in men than in women are unknown.
- Being 40 years of age or over.
- Having a large neck - people with OSA often have a neck circumference of 43 cm (17 inches) or more,
- Taking medicines that have a sedative effect - such a sleeping pills, or tranquillisers,
- Having an unusual inner-neck structure - such as an unusually narrow airway or unusually large tonsils or tongue or having a lower jaw that is set back further than normal.
Suspected risk factors for OSA
Experts have also identified a number of suspected risk factors that they believe may also contribute to OSA. These are described below.
- Drinking alcohol before bedtime.
- Smoking.
- Being menopausal - the changes in hormone levels that occur during the menopause may cause the throat muscles to relax.
- Having a family history of OSA - there may be some genes that you inherit from your parents that can make you more susceptible to OSA.
- Taking the anti-impotence medicine sildenafil (Viagra) - there is some evidence to suggest that sildenafil can cause the throat muscles to relax.
