Sleep Testing


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. Digital hardware and software is used to measure your brain waves, eye movements, muscle activity, breathing, snoring, oxygen levels, heart rhythm, body position and 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 guide you on how to properly set up your sleep test equipment.


Physiological processes routinely measured during a diagnostic PSG

  • Electroencephalogram (EEG - brain waves)

  • Electro-occulogram (EOG - eye movements)

  • Electromyogram (EMG - muscle tone)

  • Electrocardiogram (ECG - heart rhythm)

  • Oximetry (blood oxygen content)

  • Body position

  • Nasal and oral air-flow

  • Leg movements

  • Snoring and sound

Types of Sleep Studies

Overnight diagnostic sleep studiesThis 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.

Air Liquide Healthcare provide overnight home based sleep tests that you can conduct from the comfort of your own home.

Read more on sleep studies with Air Liquide Healthcare

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).

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).

Electroencephalograms We 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.

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