A sleep study records your brain and body activity during sleep

The stages of sleep range from light to deep. Each stage has characteristics that can be measured. A sleep study is a number of tests done at the same time during sleep. The tests measure specific sleep characteristics and help to diagnose sleep disorders. A sleep study may also be called polysomnogram.

The basic recordings done during a sleep study may include:

  • Electroencephalography (EEG) – This measures brain wave activity.
  • Electrooculogram (EOG) – This measures eye movement.
  • Electromyography (EMG) – This measures muscle movement.
  • Other recordings – An electrocardiogram (ECG) may be used to record the electrical activity of the heart. Video recordings may also be made of you while you sleep.

Sleep studies generally take place in a sleep lab during your normal sleeping hours. The goal is to record brain and body activity that happens during sleep so that sleep disorders can be diagnosed and treated.

What will be studied while you are sleeping

During a sleep study, the following may be measured:

  • Eye movement – The number of eye movements and their frequency or speed.
  • Brain activity – The electrical currents of the brain.
  • Limb movement – The number and intensity of movements.
  • Breathing patterns – The number and depth of respirations.
  • Heart rhythm – The electrical activity of the heart.
  • Oxygen saturation – The percentage of oxygen in the blood.
  • Acid/base balance of the stomach – The amount of acid secreted during sleep.
  • Sleep latency – The time it takes to fall asleep.
  • Sleep duration – The period of time a person stays asleep.
  • Sleep efficiency – The ratio of the total time asleep to the total time in bed.

Also, these tests may be done:

  • Multiple sleep latency tests (MSLT) measure how long it takes to fall asleep
  • Multiple wake tests (MWT) measure whether you can stay awake during specified times.

Doctors trained in sleep medicine evaluate test results to treat sleep issues. A trained sleep technician will be with you in the sleep lab during the testing period.

Reasons why you might need a sleep study

Common reasons for a sleep study include:

  • Excessive snoring
  • Sleep apnea (periods where the breath stops)
  • Daytime sleepiness
  • Insomnia (inability to sleep)
  • Narcolepsy (sudden onset of sleep)
  • Restless legs syndrome (condition causing uncomfortable leg sensations)

Nightmares during non-dream stages of sleep (sleep terrors), sleep walking or talking, and rapid eye movement disorders are less common conditions that may also require a sleep study.

There may be other reasons for your health care provider to recommend a sleep study.

To schedule an appointment with a specialist at Main Line Health, call 1.866.CALL.MLH (1.866.225.5654) or use our secure online appointment request form.