SLEEP STUDIES

Sleep studies are tests that detects abnormalities in your sleep patterns or in your breathing during sleep. All sleep studies should always be recorded by a qualified individual. This may either be an HPCSA registered Clinical Neurophysiologist or a HPCSA registered EEG Technician.

It is important that you know whether the person performing the sleep studies is registered with the HPCSA. 

Sleep disorders are a well-known major risk factor for cardiac, pulmonary and metabolic diseases. 

Diagnosis and treatment of sleep disorders is a highly specialised neurophysiology subspecialty that services the needs of Neurology, Neurosurgery, Pulmonology, ENT and primary care internal medicine.

Besides diagnosis and grading evaluation of primary sleep disorders of breathing and sleep architecture, sleep studies are an objective functional evaluation, and an early diagnostic tool, for various pulmonary function, metabolic and cardiac related diseases.

Sleep Studies are a combination of procedures consisting of: 

• Diagnostic and titrating Polysomnography

• • Limited channel screening studies for OSA

  • Full polysomnographic monitoring for all other neurological and neuromuscular disease related breathing disorders

• Multiple Sleep Latency Testing

• Maintenance of Wakefulness Testing

Polysomnography (PSG)

Polysomnogram is a test that measures electrical activity in the brain and patterns of breathing or movement during sleep that will be recorded as wavy lines on a computer screen.

Several levels of testing exist that can be done in several settings depending on what your doctor thinks the problem may be. 

Before the test, you’ll need to make sure your hair is clean and doesn’t have any hair sprays, oils or gels in it. These products can interfere with the function of the electrodes.

PSGs are non-invasive and non-painful tests.

• Some reasons why your doctor may refer you for a PSG

Concerns about your breathing or excessive snoring during sleep that may be disruptive to sleeping. Some conditions like restless leg syndrome can be seen on PSG as periodic limb movements resulting in continuous recurrent arousals that prevent restful sleep. Any abnormal behaviours, or “acting-out your dreams” that may be signs of a sleep disorder or parasomnia. Although the most common referral for PSG is obstructive sleep apnea, it is by no means the only disorder of disrupted sleep that could cause your doctor to refer you for a PSG.

• Why are there different levels of testing

There are many different types of sleep disturbances, and your doctor will choose the right level of testing for you based on your symptoms and your other medical conditions. 

What can I expect from my test

• Level One Testing

Level one testing occurs when you sleep in a sleep lab with full monitoring of your brain waves and sleep cycle, breathing airflow, breathing movements, muscle tone, snoring, heart rate, and oxygen levels in your blood. This type of testing includes monitoring the movements of your legs/arms and the position that you are sleeping in. It also includes video monitoring that can assist in determining the causes of any disruptions in your sleep. Video recording is also necessary to diagnose conditions such as sleepwalking or other sleep behaviour disorders. These disorders are referred to as parasomnias or REM behaviour disorders.

This type of study is the most sensitive for any sleep disturbances including sleep apnoea and parasomnias. By recording your brain waves and sleep stages the neurophysiologist can more accurately report on the efficiency of your sleep as well as the extent of disruption due to apnoea or movements.

• How is a level 1 PSG done

During a PSG metal discs called electrodes are pasted onto your scalp, around your eyes, below your chin, on your chest and on your legs or arms. These are small metal disks with thin wires. These electrodes measure your brain waves, eye movements, and muscle tone to determine how deeply you are asleep. The electrodes on your legs, and possibly your arms, are used to monitor for abnormal or excessive movements that may be disrupting your sleep. Video recording help the neurophysiologist and your doctor to accurately determine whether sleep disturbances are related to abnormal movement disorders or other disruptions.

• Level Two sleep studies

Level two testing is a simplified version of level one testing and records all the same variables as a level one study, except this can be done in your own home and will not include video monitoring. A level two study will still monitor your breathing, blood oxygen level changes, heart rate changes, brain waves and sleep stages, and muscle tone and body movements. This type of study is nearly identical to level one testing for determining the quality and quantity of your sleep but will not capture the same level of detail as a level one study. It can also be used to monitor your leg and body movement, detect periodic limb movement disorder (PLMD). Some more specialised sleep movement or behavioural disorders cannot be performed in the home and require additional video monitoring.

• Level Three sleep studies

Level three sleep studies, also known as sleep screening tests, use fewer sensors and does not record brain activity and cannot determine the level of sleep that you are experiencing. Sleep breathing disruptions can be reported for the total testing period but cannot be only limited to sleep. A level three (or other non-level one or two study) include variable such as breathing, heart rate, and blood oxygen levels. Level three studies are used when your doctor need to confirm a diagnosis of obstructive sleep apnoea and during a CPAP titration study to monitor effectiveness of the treatment for obstructive sleep apnoea.

• How is a level 2 or 3 home-based PSG study done

Depending on the complexity for of the test your doctor has referred you for you may need to visit a sleep lab for hook-up of the scalp electrodes and will receive training in how to self-apply the breathing sensors and start the recording at bedtime. 

Alternatively, you may receive a sleep study kit mailed to your home with instructions on how to setup the required sensors and recording device. These kits typically include sensors and electrodes to connect to your chest, finger, and possibly leg. Usually these devices record data including your breathing pattern, heart rate, and blood oxygen levels.

Multiple sleep latency test (MSLT)

A multiple sleep latency test is performed during the day for diagnosing the cause of excessive daytime sleepiness that is not related to night-time sleep distruptions. An MSLT is done during the day following a level one PSG to exclude night-time sleep disturbances.

To record a MSLT the neurophysiologist or technician will remove some of the sensors such as the airflow and breathing sensors, however the electrodes on your scalp, around your eyes, and below your chin will remain. 

During an MSLT you will be wearing comfortable street clothes and given four to five 5 – 30-minute nap opportunities in a comfortable dark and quiet room. The duration of the nap will depend on how fast you fall asleep, and each will start two hours apart. The first nap will start 1.5 – 3 hours after the end of the overnight PSG.

Before the test, you’ll need to make sure your hair is clean and doesn’t have any hair sprays, oils or gels in it. These products can interfere with the function of the electrodes.

Maintenance of wakefulness testing

A maintenance of wakefulness test is as the name suggests a test to determine how successfully you can maintain your own wakefulness when in a non-active situation. This test is not very frequently done but can be useful when both the PSG and MSLT did not reveal diagnostic information and you are still experiencing unusual sleepiness during the day. During a MWT you will wear the same sensors as for a MSLT. However, in contrast to a MSLT you will be asked to remain awake for as long as possible in a quiet non-active environment.