Sleep is a period of rest. It is an important part of your daily routine and is essential for survival. Tracking brain activity assists doctors in making a diagnosis and using the sleep study to help determine a treatment plan if a sleeping disorder such as sleep apnoea has been diagnosed. A sleep study measures heart rate, oxygen levels, sleeping position, eye movement and snoring.
A sleep study is a test which records what happens to the body when it is asleep. Another term used in place of a sleep study may be polysomnography. Depending on the situation’s severity and patient preference, it can be performed in the comfort of your home or a specialised centre. The study allows doctors to monitor brain and body functions during sleep.
Types of sleep studies
There are three types of sleep studies used to assess various sleep-related disorders: overnight pulse oximetry, respiratory polysomnography and nocturnal polysomnography (PSG).
Overnight pulse oximetry is a non-invasive sleep study designed to monitor blood oxygen and heart rate during sleep. It involves the patient wearing a device attached to the finger. Such a study can be an initial screening tool for sleep-related breathing issues.
Respiratory polysomnography is a sleep study conducted on a more comprehensive level but which can be performed at home. It involves a type 3 portable monitoring device which includes airflow monitoring, sound sensors, respiratory effort measured with bands, and pulse oximetry recordings. It is primarily used to diagnose sleep breathing disorders, including obstructive sleep apnoea and central sleep apnoea.
Nocturnal polysomnography is a more intricate sleep study designed to address a plethora of sleep-related disorders such as narcolepsy, movement disorders and parasomnias. It measures your sleep cycles and stages by recording brain waves (EEG), electrical activity of muscles (EMG), eye movement (EOG), breathing rate, blood oxygen saturation, and heart rhythm (ECG).
Periodic limb movement disorder (PLMD) is a sleep disorder that affects approximately 4% to 11% of adults and 5% to 8% of children. People with PLMD experience jerking, cramping and twitching of their lower limbs during sleep. Diagnosis for PLMD may include blood tests being requested, which rule out anaemia, deficiencies and metabolic disorders. Sleep studies, specifically PSG, can form a part of a diagnosis for PLMD. PSG monitors limb movements as well as heart rate and brain activity, and in doing so, you assess the severity of PLMD on sleep.
Newer automated scoring systems for diagnosing sleep apnoeas have also been developed. One such system called the acupebble is a novel, small wearable medical device. AcuPebble SA100 was conceived to be used by patients without the need for face-to-face training by a healthcare professional (HCP), aiming to overcome some of the limitations of current systems.
What does a sleep study show?
A sleep study is a diagnostic test that involves monitoring different body systems. It is a painless test and can help in making a diagnosis of many sleep-related conditions. During a sleep study, various tests are done to measure specific characteristics and help diagnose sleep disorders.
These different parameters and characteristics can be measured using sensors and monitoring equipment. These include:
Oxygen saturation – the percentage of oxygen in the blood
- Heart rhythm – the electrical activity of the heart
- Eye movement – the number of eye movements including the speed
- Limb movement – the number of movements
- Sleep duration – the length a person sleeps for
- Sleep efficiency – the ratio of the total time asleep to the total time in bed
- Sleep latency – the time it takes to fall asleep
- Electroencephalography (EEG): Records brain activity and identifies different sleep stages, including rapid eye movement (REM) and non-REM sleep
- Electromyography (EMG): Monitors muscle activity, helping identify episodes of muscle weakness or excessive movement during sleep
- Electrocardiography (ECG): Tracks heart rate and rhythm, assessing cardiac activity during sleep
- Respiratory Monitoring: Measures airflow, chest and abdominal movement, and oxygen levels to diagnose sleep apnoea and other respiratory disorders
Why might you need a sleep study?
Polysomnography monitors the different stages of sleep. The study can help identify disruptions to sleep.
Common reasons for a sleep study include:
- Excessive snoring
- Sleep apnoea (episodes during sleep where a person stops breathing)
- Daytime sleepiness
- Narcolepsy (sudden onset of sleep)
- Insomnia (inability to sleep)
How does a sleep study work?`
Here is a brief overview of how a sleep study works:
- The patient will have a pre-study assessment before the sleep study, where a healthcare professional will evaluate the medical history, sleeping patterns and symptoms. This assessment helps determine the need for the study and allows it to be tailored to the patient’s situation.
- The patient will then be booked in an appointment and given information on preparing for their sleep study. They will be scheduled for a night-time sleep study in a sleep centre or at home.
- The equipment setup includes electrodes and sensors attached to the patient’s body to monitor various functions and systems. The key monitoring equipment includes:
- Electroencephalography (EEG) for brain activity
- Electrooculography (EOG) for eye movements
- Electrocardiography (ECG) for heart activity
- Respiratory sensors for airflow, chest and abdominal movement, and oxygen saturation
- Snoring and sound devices
- Body movement monitors
- Throughout the night, the patient’s sleep is monitored and recorded. The data from the sensors is collected and analysed.
A sleep study is a valuable tool for diagnosing and understanding sleep issues, leading to improved sleep quality and overall health for individuals with sleep disorders.
SLEEP STUDY AT HOME?
The study can be performed in the comfort of your home. You will attend an appointment with your doctor and collect the necessary equipment needed for the study. Full instructions on how to use the kit will be provided in detail. If you are doing the test from home, different devices may be used, and each device is fitted with a sensor to track certain systems. The test would record oxygen levels, heart rate, sleeping movements, and breathing and may pick up snoring episodes.
The equipment provided will be set up with the patient’s details and calibrated. The equipment is attached to you, so you attach the black box with the elastic belts provided and use the crocodile clips as shown on the instruction sheet. It is a usual requirement to have a minimum of at least 5 hours of sleep with the equipment to obtain accurate readings.
What is a respiratory polysomnogram?
A respiratory polysomnogram, also called a respiratory polysomnography, is a sleep study that involves monitoring various respiratory parameters during sleep. A polysomnogram is a procedure that utilises ECG, EMG, EOG, airflow and respiratory effort to evaluate for underlying causes of sleep disturbances. It is primarily used to diagnose and assess sleep-related breathing disorders, such as sleep apnoea. During the study, the patient has a series of sensors and electrodes attached to them for data to be collected.
The use of limb leads depends on the patient’s situation. Limb leads are used to measure leg movements, such as in PLMD, which is associated with sleep disorders such as sleep apnoea. Limb leads are appropriate when there is a clinical need to assess limb movement alongside breathing levels. In the case of sleep apnoea, a respiratory polysomnogram provides a comprehensive evaluation of breathing abnormalities during sleep.
Worried you may have a sleep disorder?
A sleep study is an examination that uses various monitoring techniques to assess sleep patterns and diagnose sleep disorders, helping individuals achieve better sleep quality and overall health. Sleep disorders like sleep apnoea and insomnia can cause health problems if not diagnosed and treated appropriately.
There are three types of sleep studies, each of which is tailored to specific diagnostic needs: overnight pulse oximetry, respiratory polysomnography and nocturnal polysomnography (PSG). The ‘acupebble study’ and respiratory polysomnography are essential for diagnosing sleep apnoea monitoring oxygen levels and breathing patterns. They can also assist in detecting periodic limb movement disorder (PLMD). On the other hand, nocturnal polysomnography is a sleep study conducted for complex sleep disorders, offering comprehensive monitoring of various physiological parameters.
If you are concerned that you may have symptoms of various types of sleep apnoea, such as obstructive sleep apnoea or other sleep disorders (insomnia, restless leg syndrome, etc.), please visit your local GP or a specialist physician.
As a leading sleep and respiratory physician specialising in sleep apnoea and sleep-related breathing disorders, I offer diagnostic services and consultations to diagnose and treat these conditions. Please contact me if you have any further queries about sleep disorder diagnostics or want further advice on the potential treatments available.
