Doctors can diagnose some sleep disorders by asking questions about sleep patterns and habits and by getting information from sleep partners or parents. To diagnose other sleep disorders, doctors also use the results of sleep studies and other medical tests.

Sleep studies, also called polysomnography, are painless tests that measure how well you sleep and how your body reacts to sleep problems. They are also used to help your doctor diagnose sleep disorders.

The most common type of sleep study records brain waves and monitors your heart rate, breathing, and oxygen levels in your blood during a full night’s sleep.

Other ways to study your sleep include:

• More sleep latency tests measure how quickly you fall asleep during a series of daytime naps and use sensors to record your brain activity and eye movements.
• A test for maintenance of daytime alertness measures your ability to stay awake and alert.
• Activity monitors help doctors see how much you sleep and how well you sleep. They are worn at home for several days or sometimes weeks.

Sleep tests can help your doctor diagnose sleep-related breathing disorders such as sleep apnea, sleep-related seizure disorders, sleep-related movement disorders, and sleep disorders that cause extreme daytime fatigue such as narcolepsy. Doctors may also use sleep tests to help diagnose or rule out restless legs syndrome.

Your doctor will determine if you need your sleep test at a sleep center or if you can do it at home with a portable device. Sleep tests at a sleep center usually last overnight. Removable sensors will be placed on your scalp, face, eyelids, chest, limbs and a finger. These sensors record your brain waves, heart rate, breathing effort and rate, oxygen levels and muscle movements before, during and after sleep. There is a small risk of irritation from the sensors, but this disappears once they are removed.

Your doctor may do a physical exam to rule out other medical problems that may be interfering with sleep. It may be necessary blood tests to check for thyroid problems or other conditions that can cause sleep problems.