Sleep is essential for overall health, but many people experience sleep disturbances that impact their daily lives. Sleep apnoea is one such condition that disrupts breathing during sleep, leading to poor rest and potential health risks. A sleep study is a diagnostic procedure to assess sleep quality and detect sleep disorders like sleep apnoea.
We will provide a detailed understanding of a sleep study, how it is conducted, and what to expect during the process.
What is a Sleep Study?
A sleep study, medically referred to as a polysomnogram, is a test that records various body functions during sleep. It monitors brain activity, heart rate, breathing patterns, and muscle movements to assess sleep quality and identify disturbances. This painless, non-invasive procedure is commonly performed overnight in a clinic or home using portable equipment.
When is a Sleep Study Necessary?
Physicians recommend a sleep study if a person shows sleep disorder symptoms. Common signs that may indicate the need for a sleep study include:
- Loud snoring and choking during sleep
- Excessive daytime sleepiness
- Difficulty staying asleep
- Frequent awakenings at night
- Morning headaches and dry mouth
- Difficulty concentrating and memory problems
Evaluation of Respiratory Disturbances
One of the key purposes of a sleep study is to assess breathing irregularities during sleep. The test monitors:
- Sleep apnoea episodes: Pauses in breathing lasting more than 10 seconds
- Hypopnea episodes: Shallow or slow breathing that reduces oxygen levels
- Oxygen saturation: Measuring how well oxygen is delivered to the body
- Snoring and airflow: Identifying blockages in the airway
- Narcolepsy: A neurological disorder causing excessive daytime sleepiness and sudden sleep attacks.
- Restless legs syndrome: A condition causing uncomfortable leg sensations and an uncontrollable urge to move, especially at night.
- Insomnia: Difficulty falling or staying asleep, leading to poor sleep quality and daytime fatigue.
- Parasomnias: Disruptive sleep disorders, such as sleepwalking or night terrors, that affect standard sleep patterns.
Once diagnosed, healthcare professionals use the results to create personalised treatment plans. Treatment options may include continuous positive airway pressure (CPAP) therapy, oral appliances, or lifestyle modifications.
Let’s discuss the difference between sleep studies conducted at home and in clinics.
Differences Between Home and Clinic Sleep Studies
A sleep study is conducted during normal sleeping hours to assess sleep quality and identify possible disturbances. Depending on the condition being evaluated and the doctor’s recommendation, this test can occur in a hospital, a sleep study clinic, or at home.
Clinic-Based Sleep Study (Polysomnography)
A clinic-based sleep study (polysomnography) is an overnight test conducted at a hospital or sleep centre to assess sleep quality and diagnose complex sleep disorders. You’ll stay in a private room, wearing your sleepwear for comfort. Electrodes monitor brain activity, breathing, and muscle movements, while a pulse oximeter tracks oxygen levels. A sleep technologist observes your sleep, and a specialist analyses the data to confirm a diagnosis.
Home Sleep Study (HST)
A home sleep study is a simplified test mainly used to diagnose obstructive sleep apnoea. It involves fewer sensors and allows individuals to sleep in their own environment. You’ll receive portable monitoring equipment with instructions on placing sensors and starting the recording. The device tracks breathing, oxygen levels, and snoring. After returning it the following day, specialists analyse the data. However, it may not detect all sleep disorders, so a full polysomnography may still be required.
How Does a Sleep Study Work?
A sleep study uses different sensors to monitor various body functions while you sleep. Since sleep quality depends on multiple factors, using a combination of monitoring methods allows healthcare providers to get a detailed understanding of your sleep patterns. These sensors and monitoring methods are listed below.
Electroencephalography (EEG)
EEG sensors are small electrodes attached to the scalp to measure brain wave activity during sleep. This helps track sleep stages, assess sleep quality, and detect disorders like insomnia and sleep apnoea. EEG data reveals deep or REM sleep disruptions, which may interfere with physical and cognitive restoration.
Electrocardiography (EKG or ECG)
An electrocardiogram (EKG or ECG) records the heart’s electrical activity using small adhesive sensors on the chest. It helps detect irregular heart rhythms, heart rate fluctuations, and cardiovascular issues linked to sleep disorders. Sleep apnoea and other conditions can strain the heart, which is one reason why heart monitoring is an important part of the sleep study.
Electromyogram (EMG)
EMG sensors on the face and legs measure muscle movement during sleep without delivering electrical impulses. They help diagnose conditions like restless legs syndrome (RLS) and bruxism (teeth grinding). Monitoring involuntary muscle activity provides insight into movement-related sleep disorders impacting rest quality and overall health.
Electro-oculography (EOG)
EOG sensors are adhesive electrodes placed near the eyes to track eye movement during sleep. Since REM sleep plays a crucial role in memory and emotional processing, monitoring these movements helps diagnose disorders like narcolepsy and REM sleep behaviour disorder, where abnormal REM patterns disrupt normal sleep architecture.
Breathing Sensors
Breathing sensors detect airflow through the nose and mouth to monitor irregularities like snoring, shallow breathing, or apnoea episodes. These disruptions may indicate obstructive sleep apnoea (OSA), where the upper airway collapses during sleep. Identifying breathing issues allows healthcare providers to recommend treatments like CPAP therapy for better respiratory function.
Respiratory Inductive Plethysmography (RIP) Belt
A RIP belt is a flexible band worn around the chest and abdomen to track breathing effort by measuring torso expansion. It helps identify central sleep apnoea, where the brain fails to signal breathing muscles, and distinguishes it from obstructive sleep apnoea, where airway blockage is the primary issue.
Pulse Oximeter
A pulse oximeter on the finger measures blood oxygen levels and heart rate. Frequent oxygen drops during sleep suggest sleep apnoea or other respiratory issues. Low oxygen levels can cause fatigue, cognitive decline, and cardiovascular risks. This sensor helps determine if oxygen therapy or CPAP treatment is needed.
Video and Audio Monitoring
Video and audio recordings track sleep posture, movements, and sounds like snoring or gasping. This data aligns with sensor readings to detect conditions like sleepwalking, night terrors, or REM sleep behaviour disorder, where individuals physically act out dreams. It provides crucial insights into abnormal sleep behaviours requiring medical attention.
How to Prepare for a Sleep Study?
Proper preparation ensures accurate results and a more comfortable experience during your sleep study. Following these steps can help minimise disruptions and provide a more precise assessment of your sleep patterns.
- Follow pre-study hygiene guidelines: Shower before the sleep study to ensure clean skin, helping sensors adhere properly. Avoid lotions, oils, or hair products, as they interfere with monitoring devices. Remove nail polish or artificial nails, which may affect pulse oximeter accuracy.
- Watch your diet and habits before the test: Avoid alcohol and caffeine in the afternoon or evening, as they disrupt sleep patterns. Alcohol suppresses REM sleep, while caffeine delays sleep onset. Refrain from napping to ensure natural sleep during the study.
- Pack overnight essentials: Bring comfortable sleepwear, a toothbrush, and morning essentials for an overnight stay. While some labs provide necessities, packing personal hygiene items, medications, and bedtime comforts can make the experience more pleasant.
- Take medications as advised: Continue taking prescribed medications unless instructed otherwise by a doctor. Certain medications affect sleep and test results, so consult your provider in advance to determine if any adjustments are necessary.
- Inform about skin allergies: Let your provider know about any adhesive allergies to prevent skin irritation. Hypoallergenic alternatives can be used to avoid discomfort, ensuring a smooth and irritation-free sleep study experience.
By following these guidelines, individuals can ensure a practical and accurate sleep study experience, leading to a precise diagnosis and appropriate treatment for sleep-related conditions.
What to Expect After a Sleep Study?
In the morning, staff will wake you and gently remove the sensors. You can then change and leave, resuming daily activities. A sleep specialist will analyse your brain activity, breathing, oxygen levels, and muscle movement. Your results and diagnosis will be shared within a few days or weeks, depending on the findings.
What Are the Risks and Side Effects of a Sleep Study?
A sleep study is a safe, non-invasive test with minimal risks. Some may experience mild skin irritation from sensor adhesives, but hypoallergenic options are available. Discomfort from the unfamiliar setting is common but does not affect accuracy. Serious complications are rare, and any concerns can be discussed with your doctor.
What Information Will the Results Include?
Once your sleep study is complete, a sleep specialist will carefully review and interpret your sleep data. Since the test records multiple types of information about:
- Sleep stages: Amount of time spent in light, deep, and REM sleep
- Awakenings: How often do you wake up during the night?
- Breathing patterns: Whether you stop breathing or experience irregular breathing episodes.
- Snoring: If snoring is detected, it impacts your breathing.
- Body position: How different sleeping positions affect your breathing and movement.
- Limb movements: Whether involuntary movements disrupt your sleep.
- Brain activity: Any unusual patterns that may indicate sleep disorders.
A healthcare provider will reach out within a few days after your sleep study to discuss the findings. However, timelines may vary depending on the facility, so it’s best to ask when to expect your results in advance.
Understanding Your Sleep Study Results
Your provider will explain your results and may discuss these key metrics:
- Apnoea-Hypopnea Index (AHI) measures the number of sleep apnoea episodes per hour. Mild sleep apnoea ranges from 5–15 events, moderate from 15–30, and severe is more than 30 per hour.
- Sleep Efficiency refers to the percentage of time spent sleeping compared to the total time in bed. A low sleep efficiency score may indicate poor sleep quality, frequent awakenings, or insomnia.
- Oxygen Desaturation Index (ODI) measures how often oxygen levels drop below normal during sleep. If oxygen levels fall below 90% frequently, it may indicate sleep apnoea or another respiratory issue.
- Heart Rate: A normal heart rate during sleep ranges from 60–100 beats per minute. Significant fluctuations or irregularities may suggest underlying cardiovascular concerns that require further medical evaluation.
Your sleep specialist will analyse these factors and recommend a treatment plan if necessary. It is important to discuss any concerns with your provider.
What If I Am Diagnosed with Sleep Apnoea?
If your results confirm sleep apnoea, your provider may recommend treatment options based on the severity of your condition. Managing sleep apnoea is essential to prevent long-term complications. These tips will help you manage sleep apnoea.
- Lifestyle Modifications: Losing weight helps reduce airway obstruction, while avoiding alcohol and smoking prevents airway muscle relaxation. Sleeping on your side instead of your back improves airflow and minimises breathing disruptions. New weight loss injections, particularly GLP-1 agonists, may also be considered if you have a BMI over 30.
- Medical Treatments: A CPAP machine delivers a steady airflow through a mask at positive airway pressure, keeping airways open. It is the most effective treatment for moderate-to-severe sleep apnoea, significantly reducing breathing interruptions.
- Oral and Dental Devices: Mandibular advancement devices reposition the lower jaw to keep the airway open. Tongue-retaining devices prevent airway obstruction. Mouthguards help reduce teeth grinding (bruxism), which is common in sleep apnea patients.
- Surgical Options: If non-invasive treatments fail, surgery may be needed. Procedures correct structural issues in the throat, nose, or jaw to improve airflow and reduce sleep apnea episodes.
Still, if you have questions about your sleep study results or need further treatment options, please contact us. Our specialists can help you understand your diagnosis, treatment choices, and lifestyle adjustments for better sleep health.
FAQs
Q1. How long do you have to sleep for a sleep apnoea test?
A sleep study is considered valid if you sleep for at least two hours, but the more normal sleep you get, the better the data. Some people may need multiple nights for accurate results. Your healthcare provider will guide you on what’s best for your condition.
Q2. Does someone watch me during a sleep study?
Sleep studies use low-light cameras to record video and audio, but staff do not watch you continuously. They monitor readings and check the footage only if they detect unusual data. The recordings help providers compare movements with sensor readings to ensure accurate interpretations of your sleep patterns.
Q3. Can I get a CPAP without a sleep study in Australia?
In Australia, a CPAP machine typically requires a prescription, which is usually based on the results of a sleep study. Some providers may allow a trial period with a CPAP machine before formal diagnosis, but it’s best to consult a sleep specialist for proper evaluation.
Q4. Can I get up and use the bathroom during a sleep study?
Yes, you can use the bathroom during a sleep study. However, you may need assistance from the staff to disconnect some of the sensors. Policies vary by facility, so it’s best to ask beforehand about bathroom break procedures.
Q5. Does a sleep study hurt?
No, a sleep study is painless. The sensors and electrodes attached to your body won’t cause discomfort. However, removing adhesive sensors may cause slight irritation. If needed, staff can help minimise any pain after the study ends.
