Sleep Study

Sleep studies, also known as polysomnograms, are tests to diagnose and evaluate the severity of sleep disorders. Sleep disorders can be serious because they can elevate risk levels for medical conditions, such as high blood pressure, heart disease and stroke, and have also been linked to vehicular accidents and injury-causing falls.

Patients are often unaware of problems during sleep until other symptoms make them, their sleep partners or their doctors suspicious of a sleep disorder. Such symptoms include snoring; fatigue or sleepiness during waking hours; sleepwalking; waking up too early; and/or trouble falling asleep at night. In addition to diagnosing sleep disorders, a sleep study assesses how much time a patient spends in each level of sleep, and what percentage of time in bed is actually spent sleeping.

Reasons for a Sleep Study

There are several types of disorders, including the following, that sleep studies help diagnose:

  • Insomnia
  • Sleep apnea
  • Sleep-related seizure disorders
  • Parasomnia (abnormal movements or perceptions during sleep)
  • Narcolepsy

These disorders not only disturb sleep, they can be dangerous to the patient or others.

The Sleep Study Procedure

The patient arrives at a sleep laboratory a couple of hours before her or his usual sleep time. The patient is then attached to a number of machines that will monitor and record any biophysiological changes that occur during sleep. These devices typically include some or all of the following:

  • Electroencephalograph (EEG)
  • Electrooculograph (EOG)
  • Electromyelograph (EMG)
  • Electrocardiograph (EKG/ECG)
  • Nasal-airflow sensor
  • Snore microphone

These devices measure, respectively, brain-wave activity, eye movement, muscle movement, electrical activity of the heart, nasal airflow and snoring. In addition, belts are placed around the chest and abdomen to measure breathing, and an oximeter is placed on the finger to measure the amount of oxygen in the blood.

A doctor who specializes in sleep medicine analyzes the resulting data to diagnose sleep disorders and their level of severity so that an appropriate treatment plan can be devised.