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Sleep Studies, Explained

Sleep is a vital component of well-being. Subpar rest can take a toll on mental health and increase your risk for various chronic illnesses. Beyond that, sleep complaints can signal other disorders and health complications. 

If you’re struggling with sleep — whether the issue is falling asleep, staying asleep, perpetually feeling tired or something else — the first thing to do is see your primary care provider. If they suspect an underlying disorder is at play, they may recommend a sleep study either at home or in a sleep center. In this context, sleep studies aren’t research experiments — they’re tests used to diagnose sleep disorders including sleep apnea, narcolepsy and restless leg syndrome. 

Here’s how sleep studies work, when and why they’re used, and what to know before doing one. 

What are sleep studies used for?

There are three types of sleep studies a medical provider might recommend, according to Dr. Benjamin Nager, a sleep medicine specialist with Northwestern Medicine in Crystal Lake, Illinois. 

The “gold standard” sleep study is polysomnography, which typically involves an overnight stay at a sleep lab. These labs are often at independent sleep centers unaffiliated with hospitals; others are located in hospitals or at separate but affiliated clinics.

Polysomnography measures sleep by recording various physiological functions, including brain waves (EEG), eye movement, breathing rates and electrical muscle activity. Many clinics record the study on video too.

The disorder most commonly diagnosed through sleep studies (all three types) is sleep apnea, in which a person’s breathing repeatedly stops during sleep. Polysomnography is also used to diagnose conditions including:

  • Periodic movement disorders, characterized by jerky limb movements during sleep
  • Restless leg syndrome
  • Parasomnias, a group of disorders that cause abnormal sleep behaviors, such as walking (somnambulism), talking (somniloquy) and eating (sleep-related eating disorder)
  • REM sleep behavior disorder, where people physically act out their dreams
  • Sleep state misperception, where people think they’re awake for part or all of the night when they’re actually sleeping
  • Jactatio nocturnus, a rare disorder more common in children that makes people rock or bang their head during sleep

The second type of study is an at-home study, and it’s primarily used to diagnose sleep apnea. For one to three nights, a patient wears sensors on their fingertip, nostrils, abdomen and chest. This equipment remotely captures data on oxygen levels, breathing patterns and airflow.

Doctors sometimes start with at-home studies before moving onto polysomnography. But in many cases, Nager says, patients end up doing both: “I often recommend a polysomnography to begin with, because home studies can underestimate the severity of sleep apnea, and they can’t diagnose any other problems.”

The third type of study is a sleep latency test, which is primarily used when polysomnography results are inconclusive. This test takes 10 hours total and requires a patient to attempt napping every two hours. “If they go into a dreaming state more than twice in five attempts,” Nager says, “it’s generally considered to be suggestive of narcolepsy.” 

Insomnia is one sleep disorder that isn’t diagnosed through a sleep study. Instead, doctors rely entirely on self-reported symptoms, says Stephanie Jones, assistant director at the Wisconsin Institute for Sleep and Consciousness. If you’re tossing and turning all night, a doctor will typically recommend sleep hygiene improvements, such as sleeping in a cool, dark room, avoiding screen time before bed and cutting down on caffeine and alcohol. In some cases, sleep hygiene will be folded into CBT-I, a form of cognitive behavioral therapy customized for insomnia. If you still aren’t getting enough sleep, a doctor might prescribe medication. But, Jones says, a doctor won’t bring you in for a polysomnography unless they think you might have a second sleep-related condition.    

Who conducts sleep studies?

Primary care providers are the gatekeepers between patients and specialists, including sleep specialists. Sleep specialists are medical doctors. They’re usually board-certified in sleep medicine, which used to be a sub-specialty but is now a specialty in its own right. For example, Nager is a neurologist with board certification in sleep medicine; he says psychiatrists, pulmonologists and otolaryngologists also commonly practice sleep medicine. Some doctors who’ve entered the field more recently are specifically, and solely, sleep medicine doctors.

If you see a primary care doctor and report sleep apnea symptoms, such as tiredness and daytime headaches, your provider might order an at-home sleep study to rule out sleep apnea. If something else is suspected, or your test is inconclusive, you might be referred to a sleep specialist. Sometimes, Jones says, a PCP will review the results of an at-home test; other times, they’ll have a specialist review the results and make a diagnosis. If you undergo polysomnography, expect a sleep specialist to be part of the equation. They’ll be the source of any official diagnosis and subsequent treatment plan. 

Are sleep studies typically covered by insurance?

Most insurance plans cover lab-based polysomnography. Still, Nager says, there are caveats patients to know about. Since sleep medicine is a specialty, your insurance might require a referral from a primary care provider to undergo polysomnography. Also, some insurance plans only cover polysomnography if patients have already done at-home studies.

If you think you need a sleep study but your primary care doctor isn’t referring you to a specialist, Jones says it can help to use the right language to describe your problem. Instead of saying “I’m having trouble sleeping,” be specific. Use words like “snoring” and “daytime headaches,” and describe how your symptoms are affecting your daily life or compromising your ability to function. For instance, maybe your partner can’t sleep because of your snoring, or you’re so tired during the day that you’re nodding off behind the wheel. 

If that doesn’t work, Jones suggests finding a new provider who takes your sleep needs seriously.

How should you prepare for a sleep study?

While it’s normal to feel anxious beforehand, knowing what to expect can help. Your doctor should give you a step-by-step breakdown of the process, Nager says. Tell them about any concerns you have and, if you want, request a pre-study lab tour.

Try not to worry too much about how much you’ll sleep during the study. It will still be useful even if you only get two hours of sleep, Nager says, but you’ll probably get more than that. Even the most nervous patients usually still log six or seven hours of sleep, he notes. The mattresses and rooms are usually comfortable and set up to promote sleep. (They’re nothing like a hospital, with beeping machines and other interruptions). Just think of your sleep study as a hotel stay with wires attached. 

It’s not standard practice to take a sleeping pill before a study. But if you panic or can’t get to sleep after a few hours, Nager says, someone at the lab (like a nurse) might suggest a sleep aid. If you’re used to taking a sleeping pill every night, your provider might also suggest taking one during your study, to help make the sleep experience more similar to what you’re used to at home.   

What happens after your sleep study?

At some point after your study, the ordering physician — usually a sleep specialist — will review your report and, hopefully, make a diagnosis and a treatment plan. You might go back to the lab for a follow-up visit to discuss any new medications or other recommended therapies, such as a CPAP machine for sleep apnea.  

Some tests might require additional follow-up care. If you have sleep apnea and are considered high-risk for a stroke or heart problems, you may be sent back to your PCP, Nager says. If the results of polysomnography are inconclusive or narcolepsy is suspected, then you might need a sleep latency test. 

Fortunately, according to Jones, most sleep disorders are benign, meaning they’re usually treatable and non life-threatening. At times, sleep disorders can signal other, more serious health conditions. At times, sleep disorders can indicate other, more serious health conditions. For instance, REM behavior disorder can be a sign of Parkinson’s Disease, so that diagnosis warrant further testing. 

No matter the outcome, Nager says, most patients say the overnight stay was better than expected. “Some of them even go home and buy a new mattress,” he says, “because ours were so much more comfortable.” 

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