What Happens During a Sleep Study?

Medically Reviewed By William C. Lloyd III, MD, FACS
close up of sernio woman undergoing sleep study

Catching enough Zs every night is a challenge for an estimated 1 in 5 adults in America. More than 50 million Americans suffer from a chronic sleep disorder, such as insomnia or sleep apnea.

Sleep disorders prevent them from getting the recommended 7 to 8 hours of uninterrupted sleep every night. In fact, nearly 30% of adults average less than six hours of shut-eye per day.

When to Consider a Sleep Study

The long-term health consequences of not getting enough sleep can include an increased risk of high blood pressure, diabetes, obesity, depression, and cancer, as well as reduced productivity. In addition, nearly 20% of serious car crashes are associated with driver sleepiness. A sleep study may be right for you if:

  • It takes you more than a half-hour to fall asleep at night
  • You regularly need stimulants, such as caffeine, to stay awake during the day
  • You wake up frequently during the night and struggle to fall back to sleep

Preparing for Your Sleep Study

Prior to beginning a sleep study, your doctor may request that you cut back on tobacco and caffeine. You might be asked what prescription medications or over-the-counter supplements you take in case any might interfere with the sleep study. You also may be asked to take a drug screening test.

There are two main types of tests conducted during a sleep study. A polysomnogram, the most common test, measures brain activity, eye movement, and heart rate through sensors placed on the body. A multiple latency sleep test also may be used to measure brain activity and how sleepy you are. Both tests help diagnose sleep disorders and determine the causes behind poor sleep.

Sleep studies can be conducted in two ways. One requires patients to spend the night at a sleep center, where their sleep is monitored by technicians. Many sleep centers offer hotel-like rooms to enhance patient comfort. The second way allows patients to pick up a portable sleep monitor from a sleep center and take it home.

What to Expect

Whether at home or at the sleep center, the process is the same. Sensors are attached to the person’s body, including the scalp, face, chest, arms, legs and fingers, and remain on during the course of the night. These sensors record vital signs, including heart rate, blood pressure, and oxygen circulating in the blood, as well as brain activity and eye movement. An elastic belt loops around the chest and belly and measures the person’s breathing. All this information is fed into a computer so the technicians can gauge the patient’s sleep patterns.

Sleep study results show patterns of sleep and wake cycles; rapid eye movement; any abnormal breathing, such as snoring; physical movement; and the oxygen levels flowing in the blood. 

Depending on your diagnosis, treatment for sleep problems may include:

  • Developing better sleep habits
  • Losing weight
  • Quitting smoking
  • Using a mouthpiece or breathing device, if you have sleep apnea

Developing Good Sleep Habits

Once back home, it’s important to develop what experts call good “sleep hygiene” to promote a restful night’s sleep. The American Academy of Sleep Medicine recommends the following:

  • Engage in relaxing activities before bedtime, such as taking a warm bath, listening to music, or reading a book. 
  • Avoid stimulating activities, like exercise, before you turn in.
  • Keep a regular daily schedule including when you eat meals and take your medications, and try to get up at the same time every day, if possible.
  • Avoid taking naps.
  • Don’t have any caffeine after lunch or drink alcohol six hours before bedtime. Also, avoid tobacco before bedtime.
  • Don’t eat, watch TV, or play games on your smartphone or computer in bed. Keep the bedroom a dark, quiet place free of distractions.
  • Follow your doctor's advice about taking sleep aids.
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  1. Drowsy driving. American Academy of Sleep Medicine. http://www.aasmnet.org/resources/factsheets/drowsydriving.pdf.
  2. Insufficient sleep is a public health epidemic. Centers for Disease Control and Prevention. http://www.cdc.gov/features/dssleep
  3. Who needs a sleep study? National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health/health-topics/topics/slpst/whoneeds.html
  4. Types of sleep studies. National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health/health-topics/topics/slpst/types.html
  5. What to expect before a sleep study. National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health/health-topics/topics/slpst/before.html
  6. What do sleep studies show? National Heart, Lung, and Blood Institute. 
  7. Sleep hygiene—the healthy habits of good sleep. American Academy of Sleep Medicine. http://yoursleep.aasmnet.org/Hygiene.aspx. 2010.
  8. How is sleep apnea treated? National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health/health-topics/topics/sleepapnea/treatment.html.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Aug 5
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