A sleep study is a diagnostic test that records your body’s activity during sleep to help a sleep medicine physician identify whether a sleep disorder is present. If your family doctor has recommended a sleep assessment, or if you have been referred to a sleep medicine physician, understanding what a sleep study involves makes the process much less daunting.
This guide explains the types of sleep studies available, what each one measures, and what the results mean for your health.
Why Sleep Studies Are Necessary
Many sleep disorders have no visible symptoms during waking hours. Obstructive sleep apnea, for example, causes repeated breathing pauses during sleep that the person experiencing them is usually unaware of. Periodic limb movement disorder causes repetitive leg movements that the patient does not notice. REM sleep behaviour disorder involves physically acting out dreams during sleep.
The only way to accurately diagnose these conditions is to monitor what happens during sleep itself. A sleep study provides that objective data. Without it, a physician is working from reported symptoms alone, which is insufficient for a reliable diagnosis or a safe treatment plan.
Types of Sleep Studies
MedSleep offers two types of diagnostic sleep testing, and the right one for you depends on your symptoms and clinical presentation.
Level 1: In-Lab Polysomnography (PSG)
In-lab polysomnography is the gold standard in sleep disorder diagnosis. It is conducted overnight at a MedSleep sleep clinic, in a private bedroom designed to be as comfortable as possible.
During an in-lab study, a trained sleep technologist applies sensors and electrodes that monitor:
- Brain activity (EEG)
- Eye movements
- Muscle tone and activity
- Heart rhythm (EKG)
- Breathing effort and airflow
- Blood oxygen saturation
- Body position and movement
This comprehensive data set allows your sleep medicine physician to identify specific sleep stages, detect the type and frequency of respiratory events, measure arousal patterns, and diagnose conditions that a home test cannot capture, including narcolepsy, parasomnias, periodic limb movement disorder, and complex or central sleep apnea.
In-lab testing is recommended when your symptoms suggest a complex or overlapping sleep disorder, when a home test result has been inconclusive, or when CPAP titration is required to determine the appropriate treatment pressure.
Level 3: Home Sleep Apnea Test
A home sleep test uses a compact portable device to record breathing-related data while you sleep in your own bed. Home testing is appropriate for patients with a straightforward clinical presentation suggesting uncomplicated obstructive sleep apnea, without significant comorbidities that would require full in-lab monitoring.
The home device typically records:
- Breathing effort and airflow
- Blood oxygen saturation (SpO2)
- Heart rate
- Body position
A home test does not capture brain activity, so it cannot identify sleep stages or diagnose conditions beyond obstructive sleep apnea. Your sleep medicine physician will recommend the appropriate test type after your initial consultation.
What Happens Before Your Sleep Study
Before your diagnostic sleep test, your sleep medicine physician will have reviewed your symptoms and recommended the appropriate test type. You will receive specific preparation instructions from the clinic.
General preparation applies to both test types:
- Avoid caffeine after noon on the day of your test
- Avoid alcohol for at least 24 hours before the study, as it distorts sleep data
- Do not nap on the day of the test
- Arrive with clean, dry, product-free hair if attending an in-lab study, as hair products reduce electrode signal quality
- Take your regular medications as prescribed unless your physician has advised otherwise
What Happens During an In-Lab Study
You arrive at the MedSleep clinic in the evening, typically between 8 and 10 pm. A trained sleep technologist shows you to your private room and applies the monitoring sensors. Sensor application takes approximately 45 to 60 minutes.
Once you are settled, the technologist monitors your data remotely throughout the night from a separate control room. Someone is on site at all times. In the morning, sensors are removed and you are free to leave, typically by 6 or 7 am.
Most patients are concerned they will not be able to sleep. This is a normal concern. Sleep technologists account for first-night effect when interpreting data, and most patients get enough sleep for a meaningful study even if falling asleep takes longer than usual.
Understanding Your Sleep Study Results
After your study is complete, a sleep medicine physician reviews and scores the data. The results are discussed with you at a follow-up appointment. Key metrics include:
- Apnea-Hypopnea Index (AHI): The average number of breathing disruptions per hour. An AHI below 5 is normal. 5 to 14 is mild OSA. 15 to 29 is moderate. 30 or above is severe.
- Oxygen saturation (SpO2): Your blood oxygen level during sleep. Levels that drop below 90 percent repeatedly indicate that apnea events are causing physiological stress.
- Sleep stages: In-lab studies show how much time you spent in each sleep stage. Disrupted deep sleep and suppressed REM are common findings in untreated sleep apnea.
- Arousal index: The number of times per hour your brain briefly woke in response to an event. A high arousal index explains daytime fatigue even when AHI is moderate.
- Respiratory event types: Whether events are obstructive, central, or hypopneas. This distinction shapes the treatment recommendation significantly.
You should leave your results appointment with a clear diagnosis, an understanding of your key metrics, and a recommended treatment pathway. If anything is unclear, ask. A good sleep medicine physician will ensure you understand what the data means before you leave.
After Your Sleep Study: What Comes Next
If a sleep disorder is confirmed, your physician will outline the appropriate treatment. For obstructive sleep apnea, this typically means CPAP therapy or an oral appliance. For insomnia, CBT-I is the first-line treatment. For other conditions, treatment varies depending on the diagnosis.
Follow-up is an important part of the process. MedSleep’s Sleep Education resources support patients in understanding and managing their condition. If CPAP therapy is initiated, a follow-up appointment within four to six weeks is standard to review compliance data and adjust settings if needed.
MedSleep has community sleep clinic locations across Alberta, British Columbia, New Brunswick, Nova Scotia, and Ontario, offering both in-lab and home testing options.
Frequently Asked Questions
What is the difference between a sleep study and a sleep test?
The terms are used interchangeably. Both refer to the diagnostic process of monitoring your body’s activity during sleep. An in-lab polysomnography (PSG) is the comprehensive version. A home sleep test is the portable, focused version used for straightforward OSA assessment.
Will I be able to sleep with all the sensors attached?
Most patients fall asleep despite the sensors, though it may take longer than usual. Trained sleep technologists apply the sensors in a way that allows you to move and change position during sleep. Most patients report they were unaware of the sensors once asleep.
How long does it take to get sleep study results?
Results from a home sleep test are typically available within a few days of the device being returned. For Level 1 in-lab studies, results take two to three weeks as the data requires detailed scoring and physician interpretation. You will be scheduled for a follow-up appointment to review your findings once results are ready.
Can I have a sleep study if I work night shifts?
Yes. Your sleep medicine physician will take your schedule into account when planning your test. Discuss your shift pattern at your clinical consultation so the test can be structured appropriately.
What if my sleep study results are normal but I still feel terrible?
A normal result on a home test does not rule out all sleep disorders. Home tests only capture breathing-related data and cannot detect conditions like narcolepsy, periodic limb movement disorder, or parasomnias. If your symptoms persist after a negative result, discuss this with your sleep medicine physician. An in-lab study may be the appropriate next step.
Ready to book a sleep study? Book a consultation at MedSleep.
