Everyone has trouble sleeping now and then. But some have more trouble than others. If you have been experiencing trouble falling or staying asleep it may be due to a health condition such as sleep apnea, or it may be a side effect of medications, or there may be some other cause.
In some cases the only way to determine with any certainty what is at the heart of your disrupted sleep cycle may be to undergo a sleep study. The name “sleep study” does not refer to a lengthy investigation of various sleep phenomena involving thousands of people. Instead, it refers to a series of tests conducted on an individual while they are asleep.
Sleep studies may also be referred to by the clinical name “polysomnogram”. But no matter what you call it the sleep study generally involves the recording of information during sleep by way of the following machines:
The Electroencephalograph or EEG – The EEG measures brain waves.
The Electrooculogram or EOG – The EOG measures the degree of eye movement as you sleep.
The Electromyograph or EMG – The EMG records muscle activity while you sleep.
The Electrocardiogram or ECG – The ECG measures heart activity.
Video recordings – These are often made so that researchers can compare visual evidence with data recorded by the above machines.
These days we have a very clear understanding of the various stages of sleep (1). That knowledge can help in creating a baseline that can be measured against in order to diagnose sleep disorders and their origins.
In addition to the above the sleep specialists conducting the sleep study may also measure:
- Breathing patterns
- Oxygen saturation
- Sleep latency
- Sleep duration
- Sleep efficiency
- The acid balance of the stomach
A Multiple Sleep Latency Test or MSLT, which measures how long it takes you to fall asleep may also be conducted, in addition to a Multiple Wake Test or MWT which measures your ability to stay awake during a given time period.
In most cases the sleep study will be conducted in the lab of the sleep specialist during your usual sleep hours. While you are asleep a trained sleep technician will be present in the lab (typically in an adjoining room) to ensure your safety.
Why Someone Might Need a Sleep Study
It’s estimated that 1 in 4 Americans suffers from some type of sleep disturbance (2). Many of these have clearly recognizable causes, such as work-related stress or an illness such as arthritis. And in most cases people eventually return to normal sleep.
But in some cases, the cause of the sleep disturbance may be a more deep-seeded problem such as:
In addition, high blood pressure, obesity, old age and being male are also considered risk factors for serious sleep disturbances. The bottom line is that if you have chronic difficulty going to or staying asleep a sleep study may be required to diagnose the cause so that effective treatment can be devised.
The Sleep Diary
Before ordering a full-on sleep study your doctor or sleep specialist may ask you to first keep a sleep diary for a period of time. In the sleep diary you will track the times you go to sleep and wake up. You will also record how many times (if any) you wake up during the night, the reasons you wake up (nightmare, needing to use the bathroom, unknown, etc.) and whether you take any naps during the day (it’s not uncommon for daytime naps to cause nighttime sleep disturbances).
If no obvious cause emerges from the sleep diary your doctor or sleep specialist may go ahead with the sleep study. Before the study begins they will look at your entire medical history and perform a complete physical examination.
Getting Ready for the Sleep Study
The most important thing is that you do not do anything in the lead up to the sleep study that could compromise your ability to get a good night’s sleep. That typically means:
No coffee or caffeinated drinks – For a couple of days before the scheduled sleep study you should avoid coffee and other caffeinated drinks as caffeine might interfere with your ability to fall asleep.
Avoid taking naps – Not everyone does take naps during the day, and not everyone should (6). However, if you typically do you will be asked to avoid napping in the days leading up to the sleep study.
Inform the sleep specialist of any prescription medications – It is important that you provide a full accounting of any prescription or OTC medications you are taking prior to the sleep study as they may interfere with your ability to go to or stay asleep (7).
Avoiding sedatives – Unless your doctor has expressly stated that you need to take them you should avoid taking any sedatives in the lead-up to the sleep study as they may skew the results.
Avoid putting lotion or body oil on your skin – If you normally use a skin lotion or body oil you should avoid doing so on the day of the sleep study because they may interfere with the ability of the electrodes to adhere to your skin.
Don’t drink alcohol – You should avoid drinking alcohol in the lead up to the sleep study. Alcohol can sometimes help a person get to sleep, but the effect typically wears off pretty quick and the person may wake up when it does. Alcohol may also skew results of the various tests.
Don’t overeat – Eating too much can interfere with your ability to go to sleep. You may develop heartburn (8) or you may just find it difficult to get into a comfortable position if your stomach is distended.
Bring pajamas and something to read – You want to be as comfortable as possible during the sleep study, so bring comfortable pajamas and something to read to help you fall asleep.
It is understood that, because of the unfamiliar surroundings, a person is unlikely to sleep as well at the sleep lab as they would in their own bed. The goal in preparing for the sleep study is to give yourself the best possible chance of getting something close to a good night’s sleep.
The Sleep Study Process
Sleep studies have been carefully developed and refined over many years, to the point that the process is now well-established, regardless of where your sleep study is conducted. When you arrive for your sleep study you can expect things to proceed thus:
- You will be asked to remove all jewelry or other objects that could potentially interfere with the monitoring equipment.
- If you brought pajamas with you, you’ll be asked to change into them. If you did not, you will be provided a hospital gown to wear while you sleep.
- The technician will affix electrodes to your skin that will feed data to the EEG and other devices. Some of these electrodes will be affixed to your body and others to your head.
- The technician may test your blood oxygen levels using pulse oximetry (9).
- Monitoring will commence before you actually fall asleep and the lights will be turned off at about the same time.
- The technician will monitor you throughout the night to ensure there are no issues with the various electrodes and cables, and to respond if you are having a problem of some kind.
The sleep center where the study occurs is not your home, so it’s possible it may take you longer than normal to get comfortable and fall asleep. Also, some people are uncomfortable knowing they are being monitored while they sleep, but there is no realistic alternative. The technician is there to ensure your safety and to respond in the event you need anything during the night.
What the Sleep Study is Looking For
The sleep study is all about collecting data that the sleep specialist will use later to try and determine what is causing your sleep disturbance. It will record various types of physical and mental activity as your body progresses through the stages of sleep. Information gleaned from the study will include:
- How long it takes you to fall asleep.
- Whether or not you have early-onset REM sleep (10).
- Whether your sleep is continuous and if not, what may be causing the disruption.
- Whether air is flowing through your mouth and nose in a normal fashion.
- Whether or not you experience abnormal heart rate during the night.
- Whether there are any breathing abnormalities.
- Whether sleep apnea is present.
- Whether breathing abnormalities are affecting cardiac function.
- Tracking limb movements may detect seizures or other abnormalities.
In most cases it will take a few days for the sleep specialist to interpret the results of the sleep study. After that, the results are typically reviewed by a doctor, which may take several more days. In general, you can expect to get the results of your sleep study back within a week, two at the most.
What Happens Then?
What happens after the sleep study depends entirely on the results. If the data indicated a clear cause for your sleep disruptions, such as sleep apnea, your doctor will meet with you to devise an appropriate therapeutic approach, which may include a CPAP machine (11). If something else is determined to be the cause, then therapy or lifestyle changes may be recommended to address it. If no clear cause is detected by the sleep study, your doctor in concert with the sleep specialist, will work to determine the next step.
The Home Sleep Apnea Test
Above we alluded to the fact that it is not always necessary to conduct a sleep study to determine the root cause of a sleep disturbance. Sometimes a sleep diary will reveal the culprit, other times preparation for the sleep study may uncover the problem. For instance: if a person stops drinking coffee the week before the sleep study and suddenly begins to sleep well at night.
But there is yet another alternative to the full-on sleep study, and that is the home sleep apnea test. Because sleep apnea is often the underlying cause of chronic sleep disturbances it is one of the primary things sleep specialists look for. But it may be possible to detect it yourself, at home, with the help of your doctor.
Symptoms of Sleep Apnea
When we sleep the muscles in our throat relax (12). With some people, this relaxation of throat muscles causes the windpipe to collapse, narrowing the airway and interrupting normal breathing. When this happens people will snore very loudly or emit loud snorts. In some cases people dream they are suffocating and wake up suddenly, gasping for air.
This is sleep apnea, and in some cases people can have it for years without realizing it. This is especially true for people who live alone. If you find yourself still tired after 7 or 8 hours of sleep, if you wake up with a dry mouth, and/or a headache, or if you are irritable and have difficulty focusing while awake you may have sleep apnea.
Risk Factors for Sleep Apnea
Some people have a greater chance of developing sleep apnea than others. Risk factors include:
Obesity – In obese individuals, fatty deposits often accumulate in the upper airway. These can obstruct breathing once the person has fallen asleep.
Being male – Men are twice or even three times as likely to develop sleep apnea as women. The exact reason is not known but the numbers speak for themselves.
Neck size – People who have thick necks are often more likely to develop this condition.
Being older – Being older increases a person’s risk of developing a host of different health problems, including sleep apnea.
Physical predisposition – Some people are born with a narrower than normal airway that can develop into sleep apnea.
Alcohol or drug abuse – Alcohol, along with certain sedatives and tranquilizers, can cause the muscles in the throat to relax. This by itself may not cause sleep apnea, but it may aggravate it.
Allergies – People who have difficulty breathing through their nose due to allergies are at a greater risk of developing sleep apnea.
Family history – There is not yet a definitive genetic link, but evidence suggests that people with sleep apnea may pass it on to some of their offspring.
Certain medical conditions – Parkinson’s disease, diabetes, high blood pressure and congestive heart failure may increase a person’s risk of developing sleep apnea.
About Home Sleep Tests
You’ll need your doctor to prescribe it – The machine used to monitor breathing is not sold over the counter. You will need your doctor or a sleep specialist to provide you with one to take home and use.
It doesn’t monitor sleep – Unlike a sleep study a home sleep test does not measure brain, heart, eye and other activity while sleeping. Instead, it measures breathing to see if there are instances when you stop breathing (an indication of sleep apnea).
You usually monitor breathing for one night – You don’t need to monitor your breathing night after night. Typically, one night will be sufficient.
It can eliminate the need for a full sleep study – If the home sleep test reveals breathing abnormalities you may well have found the reason you’re not sleeping well, and a full sleep study will not be necessary.
Keep in mind that the home sleep test is not a cure for anything, or even a treatment. It’s a diagnostic test and that’s all. Also, it’s entirely possible that your sleeping difficulties are not caused by breathing problems. If the home test turns up no breathing issues, you may well need to have a full sleep study done.
Sleep Study FAQs
What are the Risks of a Sleep Study?
As of this writing there are no known risks associated with sleep studies besides the remote possibility that the electrodes may cause some skin irritation. Any irritation typically subsides in short order after the study, however.
Is the Test Painful?
No. This is a non-invasive test so there is nothing about it that will produce pain. As we just mentioned, about the only risk is that you may experience some short-term irritation where the electrodes are attached to your skin. If that occurs it should pass quickly.
Can I Bring a Pillow From Home?
Most sleep clinics where these studies are conducted will allow participants to bring their own pillow if it will help them sleep better. However, they tend to discourage bringing cell phones since they pose a risk of disrupting your ability to get or stay asleep. These devices may also interfere with the sleep monitoring equipment.
Is My Privacy Protected During and After the Sleep Study?
During sleep studies a video recording is made of the patient as they sleep. This is so that the sleep specialist and doctor can later view it and compare it with the data they got from the various machines. Rest assured, however, that your privacy is covered by HIPAA (the Health Insurance Portability Act) (13). The same act that ensures your privacy in the hospital or when you visit your physician.
What if I Have to Use the Bathroom During the Night?
One of the reasons a sleep technician will be in an adjoining room during the sleep study is to detach and then reattach the electrodes and other apparatus should you need to use the restroom during the night. So don’t worry. If you have to go to the bathroom just alert the technician and allow them to detach you from the equipment.
Why is So Much Equipment Needed?
A lot of things happen to your body when you sleep. Your breathing changes, your heart slows down, your muscles relax and then tense up again while you dream, and your brain experiences different levels of activity, depending on what phase of the sleep cycle you are in. So there is a lot to monitor.
The sleep specialist needs to acquire enough data while you sleep to make an informed diagnosis. As such, he or she needs all of the above-listed equipment to gather that information. None of it is superfluous. It’s all there for a reason, and all the data that is collected will be collated and cross-referenced to produce the clearest possible picture of your body and mind while you sleep.
What Treatment Will Result From the Sleep Study?
Any treatment resulting from sleep studies is entirely dependent on A) whether or not the sleep specialist is able to pin down the cause of the sleep disturbance and B) what that cause is. Keep in mind too that some people find that, after avoiding coffee for a few days prior to the sleep study, they enjoy an uninterrupted, restful night of sleep. In which case, they would likely be advised to simply avoid coffee going forward. But again, it will depend on what is discovered during the study.
Is a Sleep Study the Only Way to Detect a Sleep Disorder?
No, but it is generally considered the most effective in cases where the source of the sleep disturbance has proved elusive. A sleep diary (14) is often suggested prior to someone submitting to a sleep study. It can provide useful insights into a person’s sleep habits they may have been unaware of that are causing their problem. In other cases the sleep specialist may recommend using the Epworth Sleepiness Scale (15), which tracks a person’s degree of sleepiness at various points of the day and during various common activities.
Conclusion
If you suffer from chronic sleep disturbances that defy easy explanation you may need to ask your doctor about participating in a sleep study. The sleep study will use sophisticated instruments to monitor your mind and body while you sleep, producing a treasure trove of data that can be used to help determine the underlying cause of your sleep issues.
If you have reason to believe sleep apnea may be at the heart of your sleep disturbances you may be able to arrange a home sleep test with the help of your doctor. This type of test will monitor your breathing while you sleep and is often able to detect disruptions that indicate the presence of apnea.
In either case, if you are having difficulty sleeping don’t just accept feeling run-down all the time. Instead, talk to your doctor about whether a sleep study is right for you.
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