Patient Information Polysomnography (PSG) Author: Pulmonary Physiology & Sleep Medicine Produced and designed by the Communications Team Issue date Oct 2015 - Review date Oct 2018 - Expiry date Oct 2019 Version 1 Ref no. PILCOM1752
What is Polysomnography (PSG)? Polysomnography (PSG) is a test used to diagnose sleep disorders. It measures how well you sleep and how your body responds to sleep treatments. This test can help your doctor to fi nd out whether you have a sleep disorder and how severe it is. The test is important because untreated sleep disorders can contribute to a number of medical conditions including heart disease, high blood pressure and stroke. Sleep disorders have also been linked to an increased risk of injury, such as having a fall and road traffi c accidents. In addition to helping diagnose sleep disorders, PSG may be used to help adjust your treatment plan if you have already been diagnosed with a sleep disorder. Why is a PSG test carried out? A PSG test records your brain waves, the oxygen level in your blood, heart rate and breathing, as well as eye and leg movements. It monitors your sleep stages to identify if or when your sleep patterns are disrupted and help make a diagnosis as appropriate. Symptoms of sleep disorders Some signs and symptoms of sleep disorders include the following: It takes you more than 30 minutes to fall asleep at night. You often wake up during the night and then have trouble falling asleep again, or you wake up too early and fi nd it diffi cult to go back to sleep. You feel sleepy during the day and fall asleep within 5 minutes if you have a chance to nap, or you fall asleep at inappropriate times during the day. You have creeping, tingling, or crawling feelings in your legs that you can relieve by moving or massaging them, especially in the evening and when you try to fall asleep. You have vivid, dreamlike experiences while falling asleep or dozing. 2
You have episodes of sudden muscle weakness when you re angry, fearful, or when you laugh. You feel as though you can t move when you fi rst wake up. Your bed partner notes that your legs or arms jerk often during sleep. You regularly feel the need to use stimulants, such as caffeine, to stay awake during the day. Many of the same signs and symptoms of sleep disorders can occur in infants and children. If your child snores or has other signs or symptoms of sleep problems, discuss this with his or her doctor. Who needs a PSG test? Your doctor might not detect a sleep problem during a routine clinic visit because you are awake. Your doctor might be able to diagnose a sleep disorder based on your simple sleep tests (i.e. overnight oximetry or Embletta test) with a sleep schedule and habits. However, he or she might also need the results from a more detailed sleep test to diagnose complex sleep disorders and those not diagnosed by simple tests. Your doctor may recommend a PSG if they suspect you have: Sleep apnoea or another sleep-related breathing disorder, where your breathing repeatedly stops and starts during sleep. Periodic limb movement disorder where you involuntarily fl ex and extend your legs while sleeping. This condition is sometimes associated with restless legs syndrome. Narcolepsy, where you experience overwhelming daytime drowsiness and sudden attacks of falling or feeling limp. REM (Rapid Eye Movement) sleep behaviour disorder, which involves acting out dreams as you sleep. Unusual behaviours during sleep. Your doctor may perform this test if you do unusual activities during sleep, such as walking, moving around a lot or rhythmic movements. 3
Unexplained chronic insomnia. If you consistently have trouble falling asleep or staying asleep, your doctor may recommend a PSG test. Are there any risks? PSG is a non-invasive, painless test. Complications are rare. The most common side effect is skin irritation caused by the adhesive used to attach test sensors to your skin. What you can expect For the test you will stay overnight in Basildon Hospital on Florence Nightingale Ward. You will be asked to come to the ward in the evening so that the test can record your nighttime sleep patterns. PSG is also occasionally done during the day to accommodate shift workers who habitually sleep during the day. How to prepare The nurse/physiologist may advise you to stop or limit the use of tobacco, caffeine and other stimulants before having the test. Alcohol and caffeine can change your sleep patterns, and they may make symptoms of some sleep disorders worse. The nurse/physiologist also may ask about your regular medication. Make sure you tell them about all the medicines you re taking, including overthe-counter products. Some medicines can affect the sleep study results. You should try to sleep well for two nights before having the test. Napping the afternoon before the sleep study is usually discouraged. What to bring with you Before a sleep study, your doctor may ask you to keep a sleep diary. You will be required to record information such as when you went to bed, when you woke up, how many times you woke up during the night, and more. 4
Depending on what type of sleep study you re having, you may need to bring: Notes from your sleep diary. These notes may help your nurse/ physiologist. Pyjamas and a toothbrush for overnight sleep studies. A book or something to read / do between testing periods particularly if you have a maintenance of wakefulness test (MWT) or multiple sleep latency test (MSLT). During the PSG test You will arrive at Florence Nightingale Ward in the evening and stay overnight. You may bring items you use for your bedtime routine, and you can sleep in your own nightclothes. The room where the PSG is performed is similar to a hotel room, and it s dark and quiet during the test. You don t share the room with anyone else. The room has a shower room outside. The room has a video camera, so the nurse/physiologist monitoring you can see what s happening in the room when the lights are out. It also has an audio system, so they can talk to you and hear you from their monitoring area outside the room. After you get ready for bed the nurse/physiologist will place sticky patches with sensors called electrodes on your scalp, face, chest, limbs, and finger using a mild adhesive, such as glue or tape. While you sleep, these sensors record your brain activity, eye movements, heart rate and rhythm, blood pressure, and the amount of oxygen in your blood. Elastic belts are placed around your chest and abdomen. They measure chest movements and the strength and duration of inhaled and exhaled breaths. The sensors are connected by wires to transmit the data to a computer in the next room. The wires are very thin and fl exible. They are bundled together so they don t restrict movement, disrupt your sleep, or cause other discomfort. 5
Fig A. Patient lies in a bed with sensors attached to body The equipment monitors you throughout the night. If you need assistance, you can talk to the nurses outside at the work station. They can come into the room to detach the wires if you need to get up. This can also be done by yourself during the night you will be shown how to do this. Although you probably won t fall asleep as easily or sleep as well in the ward as you do at home, this usually doesn t affect the test results. A full night s sleep isn t required to obtain accurate PSG results. In some patients, CPAP Therapy is introduced during the study. This is called a split-night sleep study. During the first half of the night, the nurse/physiologist records your sleep patterns. At the start of the second half of the night, he or she wakes you to fi t a CPAP (continuous positive airway pressure) mask over your nose and/or mouth if you are found to have sleep apnoea. This is a small machine which gently blows air through the mask. This creates mild pressure that keeps your airway open while you sleep. The nurse/physiologist checks how you sleep with the CPAP machine. He or she adjusts the fl ow of air through the mask to fi nd the setting that s right for you. 6
At the end of the PSG, the nurse/physiologist removes the sensors or you may be instructed how to remove them in the morning. If you re having a daytime sleep study, such as a multiple sleep latency test (MSLT), or maintenance of wakefulness test (MWT), some of the sensors might be left on for that test. Multiple Sleep Latency Test (MSLT) MSLT measures how quickly you fall asleep in a quiet environment during the day. This is also known as a daytime nap study. The MSLT takes place straight after a full sleep study. It consists of five scheduled naps separated by two-hour breaks. During each nap trial, you will lie quietly in bed and try to go to sleep. Once the lights go off, the test will measure how long it takes for you to fall asleep. The series of sensors will measure whether you are asleep and determine your sleep stage. You will be awakened after sleeping 15 minutes. If you do not fall asleep within 20 minutes, the nap trial will end. Maintenance of Wakefulness Test (MWT) MWT evaluates how well a person with a sleep disorder is able to stay awake. It shows whether or not you are able to stay awake for a defined period of time. This is an indicator of how well you are able to function and remain alert in quiet times of inactivity. The test is based on the idea that your ability to stay awake may be more important to know in some cases than how fast you fall asleep. This is the case when the MWT is used to see how well a sleep disorders patient is able to stay awake after starting treatment. It is also used to help judge whether a patient is too tired to drive or perform other daily tasks. 7
After the PSG test In the morning, the sensors are removed, and you may leave the hospital ward. You are given an appointment for a follow-up visit at a later date. You can return to your usual activities after the PSG test. The measurements recorded during the PSG test provide a great deal of information about your sleep patterns. For example: Brain waves and eye movements during sleep can help your health care team assess your sleep stages and identify disruptions in the stages that may occur due to sleep disorders such as narcolepsy and REM sleep behaviour disorder. Heart and breathing rate changes and changes in blood oxygen that are abnormal during sleep may suggest sleep apnoea. Correct settings for CPAP or oxygen in case your doctor would like to prescribe these for home use. Frequent leg movements that disrupt your sleep may indicate periodic limb movement disorder. Unusual movements or behaviours during sleep may be signs of REM sleep behaviour disorder or another sleep disorder. You will not receive a diagnosis right away. The information gathered during the PSG is evaluated fi rst by the nurse/physiologist, who uses the data to chart your sleep stages and cycles to generate a medical report. That information is reviewed by your doctor. It may take a couple of weeks to receive the results of the PSG test. At a follow-up appointment, your doctor reviews the results with you. Based on the data gathered, your doctor will discuss any treatment or further evaluation that you may need. 8
Contact details For enquiries please contact: Pulmonary Physiology & Sleep Medicine Department Basildon and Thurrock University Hospitals NHS Foundation Trust Nethermayne Basildon Essex SS16 5NL Tel: 01268 394033 More information If you have any questions about the test, please do not hesitate to ask any of the people (nurse, doctor or physiologist) involved in your care. They will be happy to help you. 9
Useful sources Bloch KE, Li Y, Sackner MA, et al. Breathing pattern during sleep disruptive snoring. Eur Respir J 1997; 10: 576 586. Available at: http://erj.ersjournals.com/content/10/3/576.full.pdf Accessed September 23, 2013. Kushida CA, Littner MR, Morgenthaler T, et al. Practice parameters for the indications for polysomnography and related procedures: an update for 2005. Sleep. 2005 Apr 1; 28 (4):499-521. Available at: http://www.aasmnet.org/resources/practiceparameters/ PP_Polysomnography.pdf Accessed September 23, 2013 McArdle N, Grove A, Devereux G, et al. Split-night versus full-night studies for sleep apnoea/hypopnoea syndrome. Eur Respir J. 2000 Apr;15(4):670-5. Available at: http://erj.ersjournals.com/content/15/4/670.long Accessed September 23, 2013. Piper A, Grunstein R. Concise Clinical Review: Obesity Hypoventilation Syndrome, Mechanisms and Management. J Respir Crit Care Med Vol 183. pp 292 298, 2011. https://www.supercoder.com/webroot/upload/general_pages_docs/ document/attended_polysomnography_eval_sleep_disorders.pdf 10
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Not to be photocopied Basildon University Hospital Nethermayne Basildon Essex SS16 5NL 01268 524900 Minicom 01268 593190 Patient Advice and Liaison Service (PALS) 01268 394440 E pals@btuh.nhs.uk W www.basildonandthurrock.nhs.uk The Trust will not tolerate aggression, intimidation or violence directed towards its staff. This is a smokefree Trust. Smoking is not allowed in any of our hospital buildings or grounds. This information can be provided in a different language or format (for example, large print or audio version) on request.