Types of sleep studies

What is a Sleep Study?

A sleep study (also called a polysomnogram; PSG) is a specialised way to monitor many of your body's physiological processes while you are asleep. Tiny sensors are applied to the skin of your scalp, face, chest, fingers and legs. All SNORE Australia clinics use state-of-the-art digital hardware and software to measure your brain waves, eye movements, muscle activity, breathing, snoring, oxygen levels, heart rhythm, body position and leg movements while you are asleep.

The sensors used to perform your sleep study are non-invasive and do not hurt. There is sometimes mild, temporary skin irritation from rubbing the skin when attaching electrodes. Significant discomfort is very unusual.

Sleep studies allow many complex medical disturbances that occur during sleep to be investigated. Many of these medical conditions can cause disrupted sleep, daytime tiredness, problems with memory or concentration, and serious risk to your health.

Your comfort and safety throughout the night, and the quality of the information we record, are ensured by having trained staff on duty throughout the night when you have an overnight sleep study at one of our clinics.

The following physiological processes are routinely measured during a diagnostic PSG:

  • Electroencephalogram (EEG - brain waves)
  • Electrocardiogram (ECG - heart rhythm)
  • Nasal and oral air-flow
  • Electro-occulogram (EOG - eye movements)
  • Leg movements
  • Oximetry (blood oxygen content)
  • Electromyogram (EMG - muscle tone)
  • Body position
  • Snoring and sound

Types of Sleep Studies

Overnight diagnostic sleep studies

This is the most common type of sleep study performed, where tiny sensors are used to measure the body's physiological processes during sleep. Diagnostic polysomnograms (PSGs) are used to diagnose snoring, obstructive sleep apnoea, periodic limb movement disorder, sleep-state misperception, and other less common sleep disorders; they can also be very helpful in investigating insomnia, narcolepsy, idiopathic hypersomnolence and restless limb syndromes.

Many of SNORE Australia's attended sleep-laboratories use infra-red digital video technology to enable recording of abnormal limb movements, fits or seizures, and abnormal behaviours during sleep.

Daytime diagnostic studies

Daytime diagnostic sleep studies similar to overnight PSG can be performed in individuals who normally sleep during the day (such as shift-workers).

CPAP Titration studies

In patients whom CPAP treatment is recommended, a CPAP-titration study is used to determine what CPAP pressure is required to control snoring and obstructive respiratory events optimally. SNORE Australia uses leading CPAP equipment for these pressure titrations. Tiny sensors similar to those used during a diagnostic sleep study are also used during a CPAP-titration study.

BPAP (VPAP) and APAP Titration studies

Otherwise similar to CPAP-titration studies, these types of PSG studies involve the use of bi-level positive airway pressure (BPAP, also called variable Positive Airway Pressure - VPAP) or Automated Positive Airway Pressure (APAP) technology to treat OSA.

Multiple Sleep Latency Test (MSLT)

An MSLT is a specialised daytime sleep-study used to investigate narcolepsy and hypersomnolence. MSLTs are generally performed during the day, immediately following an overnight PSG. The test involves 4 or 5 nap periods at 2-hourly intervals throughout the day. Brain waves and eye movements are recorded to enable sleep-times and sleep-stages to be determined.

Maintenance of Wakefulness Test (MWT)

This test is used to assess a patient’s ability to maintain wakefulness throughout the day. This test is helpful in assessing the efficacy of an individual’s treatment for sleep-disorders and driving safety. MWTs are generally performed during the day, immediately following an overnight PSG. It involves four, 40-minute test periods at 2-hourly intervals, throughout the day. Patients are required to stay awake throughout each test period (brain waves and eye movements are recorded to enable wakefulness and sleep-states to be determined).


SNORE Australia offers full 28-channel EEGs in parallel with all overnight and daytime sleep-studies in patients with suspected epilepsy, nocturnal seizures, fits or 'funny turns'. EEG facilities include time-linked digital video recordings, so that convulsions or other abnormal movements during sleep can be recorded and analysed.