What Do Sleep Studies Show?

Sleep studies allow doctors to watch sleep patterns and note sleep-related problems that patients don't know or can't describe during routine office visits. These studies are needed to diagnose certain sleep disorders, such as narcolepsy and sleep apnea.

After the sleep study, your doctor will get the results. The results will include information that the sleep technician records about sleep and wake times, sleep stages, abnormal breathing, the amount of oxygen in your blood, and any movement during sleep.

Your doctor will use your sleep study results and your medical and sleep histories to make a diagnosis and create a treatment plan.

Results From a Polysomnogram

Polysomnogram (PSG) results are used to help diagnose:

• Insomnia
• Sleep-related breathing disorders, such as sleep apnea
• Narcolepsy (PSG and multiple sleep latency test (MSLT) results will be reviewed together)
• Sleep-related seizure disorders
• Parasomnias (such as sleepwalking)

If you have sleep apnea, your doctor also may use a PSG to find the right setting for you on a continuous positive airway pressure (CPAP) machine. A CPAP machine uses a small pump to gently supply air to your nose or mouth through a special mask. The right setting involves adding just enough extra air to create mild pressure that keeps your airways open while you sleep.

A PSG also helps doctors:

• Adjust CPAP settings after weight loss or gain
• Recheck your sleep if symptoms return despite treatment with CPAP
• Find out how well surgery has worked to correct a sleep-related breathing problem.

For sleep-related breathing disorders, such as sleep apnea, technicians use a PSG to record the number of abnormal breathing events. These include either pauses in breathing or dips in the level of oxygen in your blood.

In adults, when the number of events is 10 or more per hour, treatment may be needed. Children who have one to three events per hour also may need treatment.

Results From a Multiple Sleep Latency Test

MSLT results are used to help diagnose narcolepsy, idiopathic hypersomnia, and circadian rhythm disorders.

For narcolepsy, technicians study how quickly you fall asleep. The MSLT also shows how long it takes you to reach different types and stages of sleep. Sleep has two basic types: rapid eye movement (REM) and non-REM. Non-REM sleep has four distinct stages. REM sleep and the four stages of non-REM sleep occur in patterns throughout the night.

People who fall asleep in less than 5 minutes or quickly reach REM sleep may need treatment for a sleep disorder.

Results From a Maintenance of Wakefulness Test

Maintenance of wakefulness test (MWT) results may be used to show whether your inability to stay awake is a public or personal safety concern. This study also is used to show how well treatment is working.

Results From an Actigraph Test

Actigraph results give your doctor a better idea about your sleep habits, such as when you sleep or nap and whether the lights are on while you sleep. This study also is used to help diagnose circadian rhythm disorders.