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Your Sleep Study Handbook: How to Prepare and What to Expect

By - Last Updated: July 11th, 2019

Nobody likes going to the doctor so being evaluated by a sleep specialist may seem like a daunting task.

As someone who has personally gone through two in-clinic sleep studies, I can attest that while it was a long process and slightly uncomfortable, it’s nothing compared to years of suffering from sleep issues.

It’s important to remember that getting a diagnosis is the first step to living a happier and healthier life.

Getting A Referral For Your Sleep Study

Before you go to a sleep clinic, you should discuss your sleep concerns with your family physician.

Not all sleep problems require a visit to a specialist so first consulting with your personal doctor might save you a lot of time and money.

When you visit your doctor, it’s important to provide an honest and detailed description of all your sleep problems so they can do a proper assessment.

Most sleep disturbances are caused by secondary issues, such as a medical condition, illness, injury, or mental illness. During your visit, your doctor will attempt to rule out secondary factors that may be affecting your sleep.

Your doctor will take a detailed family history, do a physical examination, and order pathological tests, such as blood work. You’ll be asked personal questions about your lifestyle and home environment.

If your physician believes your sleep issues are secondary to another condition, they’ll focus on treating the condition instead of sending you to see a sleep specialist. For instance, if you’re experiencing sleeplessness because you have pain from an injury, your doctor will focus on treating your pain.

If there’s no obvious reason for your sleep problems or your doctor suspects you have a sleep disorder such as sleep apnea or narcolepsy, they’ll refer you to have an evaluation by a sleep specialist at a sleep clinic.

What Is Involved During A Sleep Study?

When you arrive at the specialized sleep center for your initial appointment, your sleep doctor or sleep specialist will assess your medical history and determine which kind of sleep study you should have.

This might including having you fill out an Epworth Sleepiness Scale.

Epworth Sleepiness Scale

To get to the bottom of how severe your sleep issues are, your doctor may score you with a test called the Epworth Sleepiness Scale (ESS). The ESS is a scientifically validated questionnaire that is used to evaluate daytime sleepiness.

The ESS asks you to rate your likelihood of falling asleep while engaged in eight different activities. These activities might include watching television, reading a book, attending a meeting, or driving.

A high ESS score indicates your average sleep propensity (ASP), or your ‘daytime sleepiness’. A higher ASP often indicates that you are suffering from a sleep disorder such as hypersomnia, insomnia, or sleep apnea.

Once your doctor has gone through your medical history and assessed your EES, they’ll decide what kind of sleep study you should undergo.


Most people undergo an in-depth sleep study is called polysomnography. A polysomnography study records your brain activity in real-time. This allows a trained polysomnography technician to track the quality of your sleep and look for problems that may show the presence of sleep disorders.

During the study, the polysomnography tech will track your breathing, blood oxygen levels, and heart rate. Specialized sensors will also test the movement of your body and legs to help determine if you’re restless.

Polysomnography measures the quality of your sleep by identifying when you sleep, how much you sleep, and if there are any disturbances in your sleep cycle.

The Human Sleep Cycle

Sleep doctors and sleep technicians can determine whether you have certain types of sleep disorders by evaluating disturbances in your sleep cycle.

Your sleep cycle is divided into two phases:

Four stages of sleep NERM and REM sleep with sleeping man
  1. Phase 1: Non-Rapid Eye Movement (NREM) sleep is composed of 3 stages, varying from light to deep sleep.
  2. Phase 2: Rapid Eye Movement (REM) sleep is composed of a single-stage when dreaming occurs and eyes move rapidly in response to dreaming.
The human sleep cycle with 1 2 3 and 4 stages of sleep
The human sleep cycle during a night of sleep.

One full sleep cycle takes 90 minutes to complete and will repeat throughout the night. Your polysomnography can monitor your sleep cycle through each sleep stage in real-time by evaluating the specific brain wave signature for each stage.

The Sleep Study Patient Experience

If your sleep doctor has determined you should undergo an overnight polysomnography sleep study, it’s nice to know what you should expect and how to prepare.

Below is a guide on what to expect before, during, and after your sleep study.

Preparing For Your Sleep Study

Before your sleep study, your specialist doctor will give you a list of protocols. This will include procedures to follow several weeks before your study and immediately before your study.

Keeping A Sleep Diary

Your sleep specialist will likely ask you to keep a sleep diary before your study. This will provide information on your long term sleep habits and will also help determine if there are any lifestyle factors that might be affecting your sleep.

At least two weeks before your study you’ll keep daily a record of the following information:

  • What time you went to bed.
  • The amount of time it took you to fall asleep.
  • What time you got out of bed in the morning.
  • The number of times you awoke during the night.
  • How refreshing you perceived your sleep to be.
  • A list of factors which may have disturbed your sleep (noise, temperature, pain, illness).
  • The number of caffeinated beverages you consumed during the day and the time of consumption.
  • The number of alcoholic beverages you consumed during the day and the time of consumption.
  • The medication you used during the day.
  • The time you spent exercising.
  • The activities you performed immediately prior to bed.

The Day Before Your Sleep Study

On the day before your sleep study, your sleep doctor will have to follow a list of important protocols. These protocols may include:

  • Restricting medications that might affect your study. This usually includes sleeping pills, some pain medications, or drugs that contain caffeine.
  • Restrictions of certain food and beverages that contain caffeine.
  • Restriction of certain physical activities, such as high-intensity exercise, that may affect your sleep.

What To Bring To Your Sleep Study

Sleep study centers provide a comfortable bed and a bathroom to use during your stay. It’s wise to pack a bag with essentials that will help you get through your study with more ease.

I always recommend that patients bring the following items to their study:

  • Toiletries. This includes toothbrush and toothpaste, deodorant, face wash, lotions, sanitary products for women.
  • Prescription medication. Only bring medications that are approved to be taken during your study.
  • Eyeglasses. You shouldn’t wear contact lenses during your study so it’s best to bring a pair of eyeglasses. 
  • Comfortable sleeping clothes. Bring clothes that can be worn loosely so they won’t restrict your movement or inhibit the sleep monitoring device. Also, bring a pair of daytime clothes to change into the next day.
  • Anything you normally require to sleep. This might include items like earplugs, and eye mask, or a stuffed animal.
  • Your Pillow. The sleep clinic will provide you with a pillow, however, most people have a very specific preference to what kind of pillow they use. To get the most out of your study, it’s best to bring a pillow from home.
  • Snacks and drinks. Hospital food isn’t the best. Pack some healthy snacks and drinks that don’t contain caffeine.

During Your Sleep Study

Most patients arrive for their sleep study in the evening, a few hours before they would normally go to bed. When you arrive at the sleep center, the staff, usually a polysomnography technician, will explain the process to you in detail.

Setting Up The Sleep Study Equipment

You’ll be taken to your room, which contains a comfortable bed and a bathroom. Some sleep study rooms are like hotel rooms while others are more clinical. This depends on where your study is conducted.

The staff will ask you to change into your sleeping clothes the duration of your study.

The technician will spend about half an hour to attach a device called an Electroencephalogram (EEG) to your head. An EEG comprises of several small electrode sensors that stick to your scalp and face with glue or tape. This process is completely painless and should cause little to no discomfort.

While most of the EEG sensors attach to your skull to measure your brain waves, some attach to the temples and face. This is to test your facial and eye movement.

Other sensors are placed on your chest, body, and legs to assess your muscle movement.

Once all your sensors are attached, the EEG is connected to a recording device by a long cord that enables you to move around freely.

The technician will also place a small device called a pulse ox loosely onto either your finger or ear to track blood oxygen levels. Airflow sensors are taped near your mouth and nose to assess breathing. Additionally, specialized elastic bands will be wrapped around your abdomen like a belt to measure body movement.

Finally, a snoring sensor, which is a small microphone, attaches to your neck. Other clinics may rely on a microphone within the room itself.

Before You Go To Sleep

Before you’re asked to get into bed go you can use the bathroom, brush your teeth, and conduct other pre-sleep routines. When you’re ready to sleep, you’ll get into bed and the technician will connect the EEG to the recording device.

The technician will perform a series of small tests to make sure the equipment is working properly. This might include having you close and open your eyes, looking in a specific direction, breathing deeply, or pretending to snore.

When it’s determined that the equipment is working, the lights are turned off and you’ll be asked to sleep. While you’re sleeping, the technologist will collect important data on your sleep and watch for any problems that may arise.

During the duration of the study, a camera will record your activity so the staff can watch you at all times. This allows them to assist you if they notice any problems.

If at any point during the night you feel uncomfortable or need to use the bathroom, you can either call the technician by an intercom or motion to the camera.

The Morning After Your Sleep Study

Your technician will wake you at a certain time in the morning. They’ll immediately disconnect your EEG from the recording device so that you can use the bathroom.

The remainder of your time in the clinic will be spent removing all of the EEG sensors and other devices. Once everything has been removed, you’ll be allowed to take a shower and clean yourself up. You’ll also be able to change into your street clothes.

Before you leave, the technician will debrief you and tell you when you can expect to get your results. Sleep data analysis time can vary so it might be a few weeks before you meet again with your sleep doctor.

Daytime Sleep Study: Multiple Sleep Latency Test

Most people will only be required to undergo an overnight Polysomnography. If you’re being tested for a hypersomnia disorder, such as narcolepsy, you’ll usually stay in the clinic for an extra day after your overnight study to conduct a multiple sleep latency test (MSLT).

Example of a multiple sleep latency test MSLT
Example of a patient’s MLST results. Sleep onset is the time in minutes it took the patient to fall asleep. REM onset is whether the patient entered REM sleep during their nap.

The MSLT assesses your daytime sleepiness by measuring how fast you fall asleep (your sleep latency) during the day. If being used to test for narcolepsy, it also assesses whether you go into REM sleep during your nap.

During your MSLT, you’ll continue to be monitored by an EEG so that the sleep technologists can see when you fall asleep and examine your sleep stages. 

During the MSLT test, you’ll stay in the same room where your polysomnography was conducted. Instead of lying in bed, you’re required to sit in a comfortable chair.

While sitting, you’re allowed to keep yourself occupied with books, TV, or your mobile phone. 

Every two hours the technician will ask you to get into the bed and turn out the light. You’ll be given the opportunity to take a 20-minute nap.

During your nap, the technologist will monitor your brain activity and calculate how long it takes for you to fall asleep.

Under normal circumstances, it can take an individual 8 minutes or more to enter stage 1 of sleep. People with hypersomnia typically fall asleep in less than 5 minutes. Individuals with narcolepsy not only fall asleep in less than 5 minutes but also go into REM stage too early.

You’ll repeat 20-minute nap a total of 5 times, every two hours to get an accurate repeated measure of how fast you fall asleep. If you fall asleep quickly during the majority of your naps, you’ll likely be diagnosed with a hypersomnia disorder.