Sleep Centre

In the past 25 years, awareness of sleep disorders has expanded rapidly. As a result, there is an increased demand for sleep studies.

There are many reasons to be referred to the Sleep Centre. Perhaps you are having difficulty falling asleep or staying asleep, falling asleep at work, sleep walking or talking, snoring, or are excessively restless at night. Or perhaps you are experiencing difficulty concentrating or waking up with morning headaches. Your family physician or nurse practitioner may send you to the Sleep Centre to have any of these symptoms investigated.

The formal name for a sleep study is overnight polysomnography (PSG). The word polysomnography is derived from three Greek words: “poly,” meaning many, “somno,” meaning sleep and “graphy,” meaning to write.

During a sleep study, information is collected from a variety of physical systems while you sleep using special sensors. This may include brain wave activity, oxygen levels, breathing effort, heart rhythms and muscles tone.

Types of sleep studies

There are three types of sleep studies.

• Level I sleep studies are full sleep studies.
• Level II sleep studies are generally referred to as home studies and use portable monitors.
• Level III sleep studies also use portable sleep monitors, however they collect only minimal information on respiratory effort, airflow, ECG (an electrocardiogram to monitor electrical signals in your heart) and pulse oximetry. These studies do not collect any information on the sleep/wake pattern across the night.

Equipment used for sleep studies

Electroencephalograph (EEG): Sensors (also called electrodes) are placed on the surface of the head to collect brain wave activity. Information collected from these sensors allows the determination of sleep versus wake.

The specific patterns also allow sleep staff to know what stage of sleep you are in (for example, REM or dreaming sleep; slow wave or restorative sleep). Valuable information is obtained from both the amount of sleep during the study and the pattern of sleep stages across the night.

Electrooculograph (EOG): Electrodes placed near the outer corners of the eye captures eye movements during sleep. These eye movements are used to identify Rapid Eye Movement (REM) sleep – more commonly referred to as dreaming sleep.

Electromyogram (EMG): Electrodes placed on the skin over muscles can monitor muscle activity and movements during sleep. EMG activity is used to determine when patients are in REM sleep. EMG activity is also used to identify leg or arm movements during sleep as well as full-body movements.

Electrocardiography (ECG or EKG): Electrodes placed on the chest collect information about heart rhythms during the night.

Respiration/Breathing Effort or Respiratory Monitoring: Thermistors and Nasal Pressure Cannula are specialized sensors that are placed under the nose or just inside the nostrils to capture either temperature changes (thermistors) or pressure changes (nasal pressure cannula) as patients breathe in and out. Variation in the flow signals are used to detect any breathing problems during the night. Respiratory bands that stretch and contract with each breath are placed around the chest and abdomen, which are a reflection of respiratory effort. Changes of respiratory effort are used to identify respiratory events during the night.

Pulse Oximetry: This determines the amount of oxygen circulating in your blood, and is measured by a small light sensor placed on a finger or toe. Interruptions to breathing may result in changes of oxygen levels in the blood. These changes are also used to identify respiratory events during the night.

Video monitoring: An infrared camera may be present in the bedroom which will allow the technologist to observe and note body position changes as well as unusual sleep behaviours. The room may also be monitored to detect sound.

Snore sensor: Either a microphone or vibration sensor may be placed near your throat. It takes 30-60 minutes to apply all the sensors prior to the sleep study.

Each patient has their own bedroom. The technicians collect the sleep study data in a nearby control room. If you require assistance during the night, the technician is there to help. Starting at approximately 6 a.m., the technician will wake patients and remove the electrodes. After completing a brief questionnaire, patients can wash up and leave.

The sleep study is analyzed and interpreted by specialized technologists and physicians with training in sleep disorders. The sleep specialist that interprets your study understands that your sleep in the laboratory may not completely match your sleep at home; this difference usually does not interfere with obtaining the necessary data from your study.

A report is created that summarizes your sleep information. A physician will then review the sleep study report and give an interpretation of the results. The sleep study contains hours of data. Results should back to your family physician or nurse practitioner within 3-4 weeks.

How to prepare for your sleep study

The items listed below are general considerations:

• Please note that napping, alcohol intake, recreational drugs or caffeine all may affect the test and can interfere with the accuracy of the results.
• Bring your valid New Brunswick Medicare card.
• Please arrive for your sleep study on time. You cannot arrive at your usual bedtime because it takes time to apply the sensors.
• Shower or bath before going for your study. Do not use hair products including gels, creams and sprays (do not wear or bring scented products with you since this is a scent-free facility). Also avoid using skin lotion, face makeup, fingernail polish or acrylic nails as these products interfere with procedures. Men who are normally clean-shaven should shave on the evening before going to the sleep laboratory. There is no need to shave off an existing beard or moustache.
• Please continue to take all medications as usual unless you have been specifically asked to stop a medication prior to your study. Bring your medications to the Sleep Centre as it does not have access to any medications.
• You will be asked to complete questionnaires before and after your sleep study. Please bring a family member or friend if you need help completing the questionnaires.
• If you are diabetic or get hungry during the night, bring a snack.
• Bring light reading material to keep you occupied.
• You may be asked to give written or spoken consent to the procedures.

What to do if you are sick? When booking your sleep study, we will provide you with information about what to do in the event of illness. If you are not sure if you should go to the Sleep Centre, please call the office by dialing 506-648-6178. Do not wait until the last minute to cancel an appointment. This time was set aside specifically for you.

We hope that your experience the Sleep Centre is a positive one.

Evaluation and management of sleep disorders can significantly improve your overall health and quality of life.

(Source: Canadian Sleep Society)