During a sleep study, your child spends about 10 hours in our sleep laboratories so that we can watch how he sleeps and monitor body functions while he’s sleeping. This is the best way for your child’s medical team to diagnose certain sleep disorders or to understand how well certain treatments are working.
A sleep study usually takes place overnight. You and your child come to the sleep laboratory in the evening and leave the next morning. This study is also called polysomnography: "poly” (many) + “som” (sleep) + “graphy” (recording). That is, the study involves recording multiple features of sleep.
If your child needs continuous positive airway pressure (CPAP) as treatment for obstructive sleep apnea or other sleep-related breathing problem, we may perform a sleep study in which your child wears a mask over his nose, and air is blown through the mask at a precise pressure. This is a CPAP study (or “CPAP calibration” or “CPAP titration”). This helps your child’s doctor determine if this treatment is effective and what air pressure is right for your child.
A multiple sleep latency test (MSLT) is a sleep study done during the day. In this test, we see how quickly your child is able to fall asleep throughout the day. We also monitor your child’s stage of sleep (dreaming and non-dreaming). This gives us a measure of how much sleepiness your child has during the daytime. It helps doctors diagnose specific sleep problems such as narcolepsy.
In sleep studies, we place sensors on your child’s body to record a number of different body functions. These include:
- brainwaves (electroencephalogram, EEG)
- eye movements (electrooculogram)
- muscle tone (chin electromyogram, EMG)
- chest movements (belts placed comfortably around the chest)
- oxygen levels (finger clip with light sensor)
- carbon dioxide levels (tube at the nose)
- heart rate and rhythm (electrocardiogram)
- arm and leg movements (electromyogram, EMG)
We also record (using both audio and video) your child sleeping so we can actually see how your child sleeps and hear how he breathes during sleep.
Q: What is a sleep study?
A: In a sleep study, you and your child spend a night in one of our sleep laboratories so that we can watch your child sleep while we monitor body functions including brain waves, heartbeat, movements and breathing.
Q: Why is a sleep study needed?
A: Sleep studies are done to help doctors diagnose a variety of sleeping problems. The test can show whether your child’s sleep is unusually light or broken, progresses normally through deep and light sleep and dreaming or is interrupted by leg jerks or other abnormal movements; it can also show whether your child has abnormal breathing patterns while he’s sleeping.
Q: What is a CPAP study?
A: For some children who experience periods of shallow or obstructed breathing during sleep, we may prescribe continuous positive airway pressure (CPAP), in which your child wears a mask through which air blows at a precise pressure to help him breathe well while he sleeps. In a CPAP sleep study, we test different air pressure levels to help us choose the best level to use for your child.
Q: What is a multiple sleep latency test (MSLT)?
A: A multiple sleep latency test is a sleep study in which we monitor how quickly your child is able to fall asleep throughout the day and the type of sleep he has. This provides a measure of how much sleepiness he has during the daytime and helps doctors diagnose specific sleep problems such as narcolepsy.
Q: What should we bring to the sleep laboratory?
A: Bring items your child will need during the night, such as pajamas, a favorite pillow and blanket, a bottle or pacifier and his usual medications. You may also want to bring a DVD of a favorite movie so your child can watch it while we’re getting him ready for his sleep study. One parent or responsible caregiver must stay with your child overnight. You may want to bring pajamas and other personal items for yourself.
Q: Can my child sleep or eat before the sleep study?
A: Don’t let your child take extra naps on the day of the study—particularly just before you come or on your way to the sleep laboratory. Your child should eat before he comes in, but he shouldn’t have caffeinated drinks or chocolate.
Q: How do I get my child ready for the sleep study?
A: Wash your child’s hair thoroughly the night before or morning of the sleep study; don’t use oil, gel or hairspray. Reassure your child that you will stay with him through the whole test and that nothing should hurt. In most cases, we will simply put sensors on his skin (mainly on his head, face, chest, stomach area and finger).
Q: What happens during the sleep study?
A: After the technologist gets your child ready for the study, we dim the lights and let your child go to sleep. You stay in your child’s room with him. The technologist may enter the room during the night to make adjustments but usually doesn’t have to wake your child up. In the morning (usually 6 a.m.), the technologist wakes your child up and removes the sensors. Most families leave by 7 a.m.
Q: What happens after the sleep study?
A: A doctor in the sleep center interprets the results of your child’s sleep study and sends preliminary results to the doctor who ordered the study and to certain other doctors involved in your child’s care. We usually send out the full report within two weeks. Technologists do not give their impressions or preliminary results before the physician interprets the study.
Questions to ask your doctor
If your child is coming to one of our sleep laboratories for a sleep study, you and your child probably have a lot of questions on your mind, such as: What does a sleep study involve? Are the sensors going to hurt my child? In these pages we’ve tried to provide some answers to questions you may have, and you should feel free to ask your child’s doctor about the sleep study, too.
At a medical appointment, it can be easy to forget the questions you wanted to ask. It’s often helpful to jot them down ahead of time so that you can leave the appointment feeling like you have the information you need and comfortable with the plan for your child’s testing and treatment.
If your child is old enough, you may want to suggest that he write down what he wants to ask his doctor, too.
Some of the questions you may want to ask include:
- What will happen during the sleep study?
- How is this test going to help in diagnosing my child’s condition?
- What should we do during the day before the study?
- What do we need to bring?
- How can I find out the results of my child’s sleep study?
If any additional questions or concerns come up before or after your child’s sleep study, call us in the Center for Pediatric Sleep Disorders at Boston Children’s Hospital.