Have you been experiencing prolonged poor sleep or excessive daytime sleepiness? Are you concerned that you might have a sleep disorder? You may have been thinking about or have booked a sleep study. Professor Robert Adams, a member of the Sleep Health Foundation's Board, has provided answers to some frequently asked questions about sleep studies to give you an understanding of when and how they’re useful, and what to expect if you’re getting one.
What disorders can be diagnosed with a sleep study?
Overnight sleep studies can be used to help diagnose sleep-related breathing disorders such as sleep apnoea, periodic limb movement disorder, sleep-related seizure disorders or certain types of epilepsy, sleep disorders that cause extreme daytime tiredness such as narcolepsy or idiopathic hypersomnolence, sleep-related movement disorders or parasomnias (such as sleepwalking, sleep-related eating disorder and sleep paralysis). It can also assist with the diagnosis of chronic insomnia.
How else are sleep disorders diagnosed?
Your history of symptoms, risk factors and other health conditions, along with questionnaires and a physical examination, including measuring blood pressure, can often identify if you are likely to have a specific sleep disorder and whether further investigations may be needed.
A sleep diary, where you record you sleep timing and patterns or a device which monitors sleep patterns, can assist in the assessment of insomnia, and help people to monitor and recognise their sleep habits.
Sometimes daytime tests, such as the Multiple Sleep Latency test or the Maintenance of Wakefulness test, where a person’s is monitored in a sleep facility during usual waking hours, can be used to assess for disorders such as narcolepsy.
It is important to recognise that a sleep study is a test, not a medical opinion, and that a final diagnosis and management plan needs to be worked out between you and your doctor, using the results of the sleep study as well as your history and personal circumstances. Sometimes other tests, such as blood tests, can help decide on management.
How do I book a sleep study?
A sleep study can be performed either in a sleep laboratory, often located within a hospital, or at home. Asleep study can be arranged after referral to a sleep or respiratory specialist who then organises the study or under certain criteria by direct referral from your GP or other specialist. To qualify for a Medicare rebate for a home-based study referred directly by your GP, a person need to be assessed as at risk for moderate-to-severe sleep apnea, using results on particular questionnaires specified by Medicare.
What happens during a sleep study?
Sleep studies involve multiple types of sensors, each tracking a specific body system or process, in order to get an in-depth assessment of sleep.
These include sensors that detect:
- brain wave activity (electroencephalography or EEG) that accurately measures your actual sleep using leads on your scalp;
- eye movements(electrooculography or EOG)which helps differentiate different stages of sleep, using leads on the side of your eyes;
- your heart’s electrical activity (electrocardiography or ECG);
- muscle activity (electromyography or EMG) with leads attached to the skin on your jaw and also your legs, to look at muscle tone in your tongue and upper airway muscles and to detect leg movements;
- airflow from your breathing through your nose or mouth;
- movement of the breathing-related muscles in your chest and abdomen (Respiratory inductive plethysmography belt);
- pulse and oxygen levels (pulse oximeter);
- body position, using a small device taped to your chest;
- noise (measures sound in decibels, such as from snoring);
- video (in the sleep laboratory) to look at movements during sleep or other behaviours such as sleepwalking.
These leads connect to a digital box. If you need to get up to go to the bathroom the staff in the lab can help you disconnect the box and re-connect when you get back to bed.
Can I do it at home?
Home-based studies are increasingly being used, especially in people felt to be at high risk for sleep apnea. A home-based study would usually involve you coming into the sleep laboratory in the late afternoon/early evening for the equipment to be attached and then going home to sleep as usual. You then bring the equipment back the next day. Home sleep studies usually involve less sensors then an in-laboratory study, and focus more on cardiac and respiratory measurements. A home study is less likely to be used if abnormal movements during sleep are a concern, or if the person has significant other health conditions. The decision whether a home study is appropriate is best decided in consultation with your doctor.
How soon do I find out results?
Sleep studies are complex tests that record over 1 gigabyte of digitised data. They usually require asleep technician to evaluate or “score” the study which then has to be reviewed and reported on by a sleep physician. This process can take up to 2-3 weeks to be finalised in some instances. If urgent, a preliminary assessment and report can be done sooner.
How much does a sleep study cost? Is it covered by Medicare or are there subsidies available?
Sleep studies will be subsidised by Medicare when performed through a hospital or sleep laboratory organised by your specialist, or if referred by your GP when the criteria for a Medicare-rebatable study is met. This will often cover the full cost of the study. At other times a gap payment may be charged. The group or hospital conducting the study should inform you about any costs or charges before the study is performed.
Read more about Sleep Studies here.
Read Professor Robert Adams bio here.