Who Needs a Sleep Study?
If you often feel very tired during the day—even though you spent enough time in bed to be well rested—talk to your doctor. This is a common sign of a sleep disorder. A number of sleep disorders can disrupt your sleep, leaving you sleepy during the day.
Other common signs of sleep disorders include the following.
- It takes you more than 30 minutes to fall asleep at night.
- You awaken often during the night and then have trouble falling back to sleep, or you awaken too early in the morning.
- You feel sleepy during the day and fall asleep within 5 minutes if you have an opportunity to nap, or you fall asleep at inappropriate times during the day.
- Your bed partner claims you snore loudly, snort, gasp, or make choking sounds while you sleep, or your partner notices your breathing stops for short periods.
- You have creeping, tingling, or crawling feelings in your legs that are relieved 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.
- 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 first wake up.
- Your bed partner notes that your legs or arms jerk often during sleep.
- You regularly feel the need to use stimulants to stay awake during the day.
Describe your signs and symptoms to your doctor. It's important to note how tired you feel and whether your signs and symptoms affect your daily routine. Early signs of sleep disorders aren't easy to detect during routine visits. There are no blood tests for sleep disorders, and the doctor isn't watching you sleep.
Your doctor can decide whether you need a sleep study. A sleep study allows your doctor to observe sleep patterns and to diagnose a sleep disorder, which can then be treated.
Certain medical conditions have been linked to sleep disorders. These include heart failure, coronary artery disease, obesity, diabetes, high blood pressure, and stroke or transient ischemic attack (TIA, or "mini-stroke"). If you have one of these conditions, talk with your doctor about whether it would be helpful to have a sleep study.
What To Expect Before a Sleep Study
Before a sleep study, your doctor may ask you about your sleep habits and whether you feel well rested and alert during the day.
You may be asked to keep a sleep diary or sleep log. You will record information such as when you went to bed, when you woke up, how many times you woke up during the night, and more.
What To Bring With You
Depending on what type of sleep study you're having, you may need to bring:
- Notes from your sleep diary or sleep log. These may be helpful to your doctor.
- Pajamas and a toothbrush for overnight sleep studies.
- A comfortable pillow.
- A book or something to do between testing periods if you're having a multiple sleep latency test or a maintenance of wakefulness test (MWT).
How To Prepare
You may need to stop or limit the use of tobacco, caffeine, and stimulants before having a sleep study. Your doctor may ask you about alcohol, medicines, or other substances that you take and about allergies that you have.
You may routinely take medicine that affects your sleep patterns. If so, a sleep specialist will help you plan how to take it during and possibly before the test.
You should try to sleep well the night before you have an MWT, because you will have to try to stay awake during this test. If you're being tested as a requirement for a transportation- or safety-related job, you may be asked to take a drug-screening test.
What To Expect During a Sleep Study
Sleep studies are painless. Parents can go with their children to a sleep study.
The polysomnogram (PSG), multiple sleep latency test (MSLT), and maintenance of wakefulness test (MWT) are usually done at a sleep center. The room the sleep study is done in may look like a hotel room. A technician makes the room comfortable for you and sets the temperature to your liking.
Most of your contact at the sleep center will be with nurses or technicians. You can ask them any questions that you may have about the sleep study.
During a Polysomnogram
Sticky patches called sensors are placed on your scalp, face, chest, limbs, and a finger. While you sleep, these devices 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 each exhaled breath.
Wires attached to the sensors transmit the data to a computer in the next room. The wires are very thin and flexible and are bundled together to minimize discomfort. You will be able to roll in any direction.
A technician in another room monitors the recordings as you sleep. He or she fixes any problems with the recordings that occur. The technician also helps keep you comfortable and disconnects the equipment if you need to go to the bathroom.
When it's time for you to sleep, the room will be dark and quiet.
If you show signs of sleep apnea, you may have a split-night sleep study. During the first half of the night, the technician records your sleep patterns. At the start of the second half of the night, he or she wakes you to fit a continuous positive airway pressure (CPAP) mask over your nose and mouth.
The mask is connected to a small machine that gently blows air through the mask. This creates mild pressure that keeps your airways open while you sleep.
The technician checks how you sleep with the CPAP machine. He or she adjusts the flow of air through the mask to find the setting that's right for you.
At the end of the PSG, the technician helps you out of bed and removes the sensors. If you're having a daytime sleep study, such as an MSLT, some of the sensors may be left on for that test.
During a Multiple Sleep Latency Test
The MSLT is a daytime sleep study that's usually done after a PSG. Sensors on your scalp, face, and chin usually are used for this test. These sensors record brain activity. They show various stages of sleep and how long it takes you to fall asleep. Sometimes your breathing also is checked during an MSLT.
A technician in another room watches these recordings as you sleep. He or she fixes any problems with the recordings that occur.
Starting 1.5 to 3 hours after you wake from the PSG, you're asked to relax in a quiet room for about 30 minutes. The test is repeated three or four times throughout the day. This is because your ability to fall asleep changes throughout the day.
You get 2-hour breaks between tests. You need to stay awake during the breaks. The MSLT records whether you fall asleep during the test and what types and stages of sleep you have. Sleep has two basic types: rapid eye movement (REM) and non-REM. Non-REM sleep has four distinct stages. REM sleep and the four stages of non-REM sleep occur in patterns throughout the night.
The types and stages of sleep can help your doctor diagnose a sleep disorder such as narcolepsy, idiopathic hypersomnia, or a circadian rhythm disorder.
During a Maintenance of Wakefulness Test
This sleep study occurs during the day. It's usually done after a PSG and takes most of the day. Sensors on your scalp, face, and chin are used to measure when you're awake or asleep.
You sit quietly on a bed in a comfortable position and look straight ahead. Then, you simply try to stay awake for a period of time.
An MWT typically includes four trials lasting about 40 minutes each. If you fall asleep, the technician will wake you after about 90 seconds. There are usually 2-hour breaks between trials. During these breaks, you can read, watch television, etc.
If you're being tested as a requirement for a transportation- or safety-related job, you may need a drug-screening test before the MWT.
During an Actigraph Test
You don't have to go to a sleep center for this study. The actigraph is a small device that's usually worn like a wristwatch. You can go about your normal daily routine while you wear it. You remove it while swimming or bathing.
The actigraph measures your sleep–wake behavior over 3 to 7 days. Results give your doctor a better idea about your sleep habits, such as when you sleep or nap and whether the lights are on while you sleep.
You may be asked to keep a sleep diary while you wear the actigraph.
What To Expect After a Sleep Study
Once the sensors are removed after a polysomnogram, multiple sleep latency test, or maintenance of wakefulness test, you can go home. If you used an actigraph to measure your sleep–wake behavior, you return it to your doctor's office.
You won't receive a diagnosis right away. Your primary care doctor or sleep specialist will review the results of your sleep study or sleep studies. He or she will use your medical history, your sleep history, and the test results to make a diagnosis.
It may take a couple of weeks to get the results of your sleep study. Usually, your doctor, nurse, or sleep specialist will explain the test results and work with you and your family to develop a treatment plan.
What Do Sleep Studies Show?
Sleep studies allow doctors to watch sleep patterns and note sleep-related problems that patients don't know or can't describe during routine office visits. These studies are needed to diagnose certain sleep disorders, such as narcolepsy and sleep apnea.
After the sleep study, your doctor will get the results. The results will include information that the sleep technician records about sleep and wake times, sleep stages, abnormal breathing, the amount of oxygen in your blood, and any movement during sleep.
Your cardiologist will use your sleep study results and your medical and sleep histories to make a diagnosis and create a treatment plan.