Sleep Study Test
Overview
A sleep study, also called polysomnography (PSG), helps detect different sleep disorders by checking how the body works during sleep. This test records several key functions, such as brain activity, blood oxygen levels, heart rate, and breathing patterns.
It also tracks eye movements and leg movements throughout the night. Specialists use the information to see what happens in the body while someone is sleeping.
Where the Test Is Done:
- Hospital units or dedicated sleep centers often conduct sleep studies.
- Some people who sleep during the day, such as shift workers, take this test during their usual rest hours.
- Home tests are available, especially for conditions like obstructive sleep apnea.
Ways the Test Is Used:
- Diagnosis: Identifies the type of sleep disorder and measures its severity.
- Treatment Planning: Helps doctors decide on or change a treatment strategy.
Types of Home Studies:
| Device Type | Tracks | Common Use |
|---|---|---|
| Standard Devices | Breathing, oxygen, heart rate | Obstructive sleep apnea |
| Advanced Devices | May monitor blood vessels | Detailed data for doctors |
Health professionals use information from a sleep study to select or adjust therapies for better sleep health.
Reasons for Sleep Study Testing
Doctors use sleep studies to discover what causes a person’s sleep problems. These tests track changes in sleep cycles and stages to spot anything unusual that could point to a specific sleep disorder.
By monitoring how a person’s body acts while they sleep, sleep studies can detect problems like breathing interruptions, unusual movements, or sudden awakenings.
Common reasons for a sleep study include:
| Condition | Description |
|---|---|
| Sleep apnea | Breathing starts and stops repeatedly during sleep, often leading to loud snoring or choking. |
| Periodic limb movement disorder (PLMD) | Repetitive leg movements that disrupt sleep, sometimes linked with restless legs syndrome. |
| Narcolepsy | Extreme daytime tiredness and the chance of falling asleep suddenly. |
| REM sleep behavior disorder | Moving or acting out dreams during REM sleep. |
| Sleepwalking and other nighttime activities | Walking, moving around, or showing repeated motions while asleep. |
| Chronic insomnia | Ongoing trouble falling asleep or staying asleep night after night. |
| Other sleep problems | Issues like hypersomnia or unexplained daytime sleepiness. |
Polysomnography watches for signs such as changes in brain waves, muscle movements, breathing patterns, and oxygen levels. This helps the medical team see if interruptions in the usual sleep cycle are linked to a known condition.
Sleep studies are important for diagnosing obstructive sleep apnea, where blocked airways cause breathing to stop many times. They also help confirm diagnoses like PLMD, narcolepsy, or unexplained insomnia.
Doctors use the sleep study results to decide on treatment steps. This could include medications, devices that help with breathing at night, or behavioral changes to improve sleep quality.
Possible Complications
Polysomnography is usually safe and does not cause pain. The main reported issue is minor skin irritation. The adhesive used to hold the test sensors on the skin can cause this. Most common side effects:
- Mild redness
- Itching
- Temporary marks
Serious complications are extremely rare and unlikely to occur in most patients.
How You Prepare
Before a sleep study at a sleep lab or sleep center, avoid foods and drinks with alcohol or caffeine in the afternoon and evening. These substances affect your sleep and may make it harder for the sleep technologist to get accurate results.
Skipping naps during the day also helps ensure you are tired and sleep better during the study. Take a bath or shower before you arrive, but do not use lotions, colognes, gels, or makeup because these can prevent the sleep technology sensors from working well.
Checklist to Bring
- Comfortable pajamas
- Toothbrush and toothpaste
- A change of clothes for the next day
- Any required medication
If you do the test at home, sleep technologists or staff will explain how to use the equipment. Ask questions if instructions are not clear.
What You Can Expect
What Happens While the Sleep Test Takes Place
People usually arrive at a sleep center in the evening to begin the study. Each person receives a private room with a comfortable bed and a bathroom. The atmosphere is designed to be quiet and relaxing—similar to a simple hotel room—to help the person feel at ease.
Before bedtime, individuals are allowed to bring familiar items from home, such as sleepwear or toiletries, to maintain a normal nighttime routine. A polysomnography technologist is available to assist with preparation.
The technologist gently attaches sensors to the scalp, temples, chest, and legs using mild adhesive or tape. These sensors are connected by long wires to a computer, allowing for free movement during sleep.
In addition, a small clip is placed on a finger or ear to monitor blood oxygen levels throughout the night. Here is what is typically monitored during the test:
| Feature | Monitored by | Purpose |
|---|---|---|
| Brain waves | EEG sensors | Record brain wave activity. |
| Eye movements | Electrodes | Detect REM and other sleep stages. |
| Heart rate | Electrodes | Track changes in heartbeat. |
| Breathing patterns | Chest/abdomen straps | See if breathing is regular or stops. |
| Blood oxygen level | Fingertip/ear sensor | Measure oxygen throughout the night. |
| Body position | Sensors/video | Identify posture during sleep. |
| Chest movement | Straps | Monitor breathing effort. |
| Limb movement | Electrodes | Detect twitching or restlessness. |
| Noises (snoring) | Microphone | Record sounds made during sleep. |
The sleeping area may have a low-light video camera and intercom system. This lets technologists see and communicate with the patient during the night from their monitoring area.
If special equipment is needed, like a positive airway pressure (PAP) machine, a technologist will help set it up. PAP machines, such as CPAP and BPAP, use a mask to provide steady or changing air through the airways, keeping them open during sleep apnea episodes.
Patients may try on masks before sleeping, making it easier to use if required later. During the night, technologists remain available. If a person needs assistance, they can speak through the intercom. Technologists can enter the room if sensors need adjusting or if the person needs to get up.
It is common not to sleep as well at a sleep center as at home, but this usually does not affect the test findings. The main goal is to capture enough information about sleep and body functions during the night. A full night’s sleep is not always necessary for useful data.
People who use a home sleep apnea test follow instructions for attaching the sensors and starting the device. Sometimes, they keep a sleep log to record details about when they went to bed and woke up.
Following the Sleep Study
In the morning at the sleep center, technologists gently remove the sensors and wires. People can then get dressed and leave. Most return to normal daily activities right away. Any sleepiness from the overnight study should be mild.
A follow-up appointment with the referring healthcare provider is usually arranged. At this visit, the provider explains the results and discusses any treatment. People who complete the test at home remove the sensors themselves after waking.
The equipment usually gets returned by mail or is brought to the office. In some cases, devices are disposable and can be thrown away, making the process simpler.
No special care is needed after polysomnography, and there are no lasting effects from the sensors or the devices used. Most people complete their day as normal after the study.
Test Findings
Sleep studies gather a range of measurements to examine a person’s sleep cycle and identify any disruptions. Brain activity and eye movements help determine which stages of sleep a person moves through during the night.
By observing these patterns, healthcare professionals can detect interruptions in the normal progression of sleep stages—potential signs of narcolepsy or REM-related disorders.
Heart rate, breathing, and blood oxygen levels are also tracked. Abnormal changes in these indicators may point to sleep apnea or other breathing problems. These measurements provide valuable insights that guide both diagnosis and treatment planning.
If a person uses sleep-related technologies—such as positive airway pressure (PAP) machines or supplemental oxygen—a sleep study allows the healthcare team to assess how well these devices are working. Based on the findings, they can adjust settings and offer better support for home use.
Additional behaviors, such as frequent leg movements, are monitored as well. Repetitive leg activity that disrupts sleep may suggest periodic limb movement disorder. Unusual movements or actions during REM sleep may point to REM sleep behavior disorder or other neurological sleep problems.
After the study, a polysomnography technologist reviews the recorded data and charts the person’s sleep stages and any interruptions. These findings are then sent to the healthcare provider for further evaluation.
If a home-based sleep test doesn’t provide enough information, the provider may recommend a follow-up study at a clinic.
- Technologists collect and review data.
- Home testing may require clinic follow-up.
- Healthcare provider discusses next steps and possible treatments.
| Measurement Tracked | Suggests |
|---|---|
| Brain waves & eye movements | Sleep stage issues, narcolepsy, REM disorders |
| Heart rate, breath & oxygen changes | Sleep apnea |
| Frequent leg or body movements | Limb movement disorder, REM disorders |
