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Southern Cross Medical Library

The purpose of the Southern Cross Medical Library is to provide information of a general nature to help you better understand certain medical conditions. Always seek specific medical advice for treatment appropriate to you. This information is not intended to relate specifically to insurance or healthcare services provided by Southern Cross. For more articles go to the Medical Library index page.

Obstructive sleep apnoea (OSA)

Sleep apnoea is a common and potentially serious condition in which a person stops breathing during sleep. Typical symptoms include snoring, not feeling refreshed on waking, day-time sleepiness, altered mood and morning headaches. 
There are two types of sleep apnoea: obstructive sleep apnoea (the more common type) and central sleep apnoea (which is rare). This article discusses obstructive sleep apnoea (OSA), including causes and treatment options.  OSA can occur at any age (including infancy) but is most common in middle-aged males. In New Zealand OSA is estimated to affect at least 4% of men and at least 2% of women.


In deep sleep, the muscles of the throat relax.  This does not normally cause any problems with breathing. However, in OSA the muscles at the back of the throat become so relaxed during sleep that part of the airway is closed off. A person with OSA keeps trying to breathe but no air enters the lungs and the level of oxygen in the blood drops (hypoxia). This eventually leads to semi-wakening and breathing resumes, usually accompanied by a loud snort or gasp.
The person affected by OSA is often unaware that they have woken and immediately returns to sleep. Once asleep the muscles relax again and the whole cycle recurs. This cycle can occur hundreds of times during sleep which, like insomnia, reduces the quality and benefits of a good night’s sleep.  Loud, bothersome snoring is also a feature of OSA.

The risk of OSA is higher if:

  • A person is overweight.  Excess weight on the outside of the throat increases pressure on the inside of the throat, which in turn narrows the airway.
  • Alcohol, tranquillisers or sleeping tablets are used prior to going to sleep. These can excessively relax the muscles making people more susceptible to OSA.
  • A condition that leads to excess tissue in the airway is present eg: enlarged tonsils or jaw deformities.
  • Nasal obstruction is present.
There are a number of signs and symptoms that may indicate that OSA is occurring. Often, the first indication is reports from others in the household about noisy snoring while asleep.

OSA can lead to:

  • Waking up feeling as if you haven't had enough sleep
  • Morning headache
  • Dry or sore throat
  • Feeling sleepy throughout the day
  • Difficulty concentrating
  • Loss of interest in sex and impotence in males
  • Memory loss
  • Personality change
  • Grumpiness and bad temper. 

OSA and other health problems

In addition to its possible impact on quality of life, some studies have shown that people with OSA are at greater risk of developing the following health conditions:

Due to feeling sleepy throughout the day there can be a propensity to fall asleep while driving, which is obviously very dangerous. 


As there can be many reasons for disturbed sleep or daytime sleepiness (including rare conditions such as narcolepsy) so diagnosing OSA can be difficult. If OSA is suspected, referral to a respiratory physician and/or an otolaryngologist (ear, nose and throat specialist) may be required.
A doctor will first take a detailed history of the problem and will examine the throat for signs of narrowing. It may often be helpful for the person's spouse/partner to be present, as they may be better able to explain what happens to the person during sleep. 
Tests may be used to confirm the diagnosis. Polysomnography is the most comprehensive medical test undertaken to confirm OSA. This involves an overnight stay in a special sleep clinic. Before going to sleep for the night the person is attached to a number of leads or wires to monitor what happens during sleep. Blood oxygen levels, brain activity, eye movement and other indicators are assessed.


OSA needs to be managed firstly through lifestyle changes, often in combination with other treatments.
Lifestyle and behavioural changes

In cases of mild OSA, lifestyle changes may lead to improvement in the condition.  Changes include:

  • Weight loss - as even a small loss in weight can improve symptoms
  • Avoiding alcohol for at least a few hours prior to going to sleep
  • Avoiding sleeping tablets or tranquillisers
  • Taking measures to assist sleeping on one's side rather than on one's back, as OSA can often be worse when sleeping on the back
  • Quit smoking
  • Regular exercise.
Positive airways pressure therapy
Continuous positive airways pressure (CPAP) is the most common treatment for obstructive sleep apnoea. It involves the use of a pump which delivers low pressure air into the airways via tubing and a mask fitted to the nose. It is worn during sleep and delivers enough pressure to keep the airway open during sleep. The amount of pressure required to maintain an open airway varies with each individual.  
If the results of the sleep study clearly indicate OSA, a CPAP machine is often applied and adjusted to the appropriate settings while the study is in progress. It may be necessary to return to the sleep clinic after the study to receive training on how to properly use the CPAP machine at home. Many people find they feel much better within a few days of commencing CPAP as they get the benefit of deep restorative sleep that they previously lacked.
Variations of positive airways pressure therapy devices are auto-titrating CPAP, in which the levels of pressure are adjusted if the device senses increased airway resistance, and Bilevel positive airway pressure (BiPAP) which delivers a pore-set level of pressure when you breathe in and a different level of pressure when you breathe out.
Dental appliances
There are a number of dental appliances or devices available that can help to hold the jaw and tongue in a particular position in order to help maintain an open airway. These need to be fitted by a dentist or orthodontist and can have side effects such as damage to teeth and soft tissues. They are most effective in cases of mild OSA.
Surgery may be an option to address specific abnormalities that contribute to the obstruction of airways, including procedures to remove the tonsils and adenoids, correct abnormalities in the nasal passages, and remove excess tissue from the back of the throat or tongue.  Surgery can also improve tolerance of nasal CPAP and improve effectiveness of dental devices.  Some surgical procedures that are used in the treatment of snoring and OSA are discussed in Southern Cross's Snoring Medical Library article.  An individual patient should discuss with their doctor those procedures, if any that might be relevant to their specific situation.  

Further support

The Sleep Apnoea Association of New Zealand is a support group that provides information and support to people with sleep apnoea and their families.
Contact details are as follows:
Sleep Apnoea Association of NZ Inc.
PO Box 88
Hamilton 3240
Phone: 021 344 253


Asthma and Respiratory Foundation NZ (2017). Obstructive sleep apnoea (Web Page). Wellington: Asthma and Respiratory Foundation New Zealand. [Accessed: 30/06/17]
Downey III, R. (2017). Obstructive sleep apnea (Web page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. [Accessed: 30/06/17]
Mayo Clinic (2016). Norovirus infection (Web Page). Rochester, NY: Mayo Foundation for Medical Education and Research. [Accessed: 30/06/17]
O’Toole, M.T. (Ed.) (2013). Obstructive sleep apnea. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis, MI: Elsevier Mosby.
Last Reviewed - June 2017
Go to our Medical Library Index Page to find information on other medical conditions.