If you are having issues with sleep, your doctor may order a sleep study or polysomnogram (PSG) that can help diagnose serious sleep disorders, including sleep apnea, narcolepsy, sleep-related seizure disorders, and other conditions that can compromise your health.
The overnight study is typically performed in a hospital or laboratory, often designed to look like a bedroom.
Physicians generally request a study when patients complain about feeling tired or present with other symptoms of sleep disorders such as loud snoring, frequently waking up gasping for breath, having difficulties falling or staying asleep, or experiencing a crawling sensation in the legs.
Before undergoing a PSG, a doctor may first ask a patient to keep a sleep history. This is a log of time spent sleeping or trying to sleep.
For example, the patient might record how long she was awake before she fell asleep, how long she slept, and how sleepy she felt during the day. Additionally, the patient may be asked if there were problems such as night terrors, sleep apnea, snorting, or gasping.
The patient's partner may also be asked to participate in keeping the sleep diary. The log might be kept for several weeks.
What to Expect
When you arrive for your sleep study, you will be welcomed and shown to your "bedroom" where your sleep test will take place. Once you change into your pajamas, a trained sleep technician will place lightweight monitoring wires/devices on your head, face, legs, arms, chest, and fingers.
During sleep, the devices will record information such as muscle movement, blood oxygen level, heart rate, blood pressure, breath frequency, eye movements, and brain activity. The results will be forwarded to your doctor for a diagnosis.
The sleep test is painless and in some circumstances may be performed at home. The PSG may be followed by a Multiple Sleep Latency Test (MSLT). This test is used to measure daytime sleepiness. During this test, patients wear monitoring devices on the scalp and face.
The patient must then take 20-minute naps every two hours during normal awake time. The study tracks how quickly the patient falls asleep and the time it takes for the patient to reach various sleep stages during the naps.
Typically, people do not fall asleep during these sessions, but those who are asleep within five minutes generally have a sleep disorder. This is also true for those who fall asleep during the nap and then move quickly into REM stage (deep sleep).
Results may be used to show whether your inability to stay awake is a public or personal safety concern or to check your response to treatment.
Other Sleep Diagnostic Tests
There are other sleep tests that doctors may order for patients, based on specific symptoms. One is the Maintenance of Wakefulness Test, which measures a person's ability to stay awake and alert. This diagnostic test is usually completed the day after a PSG and takes most of the day.
Another type of sleep study is an actigraphy, which helps diagnose sleep disorders related to jet lag and shift work. The individual wears a small actigraph around his or her wrist for several days and nights. This allows the doctor to track the patient's sleep and nap schedule - and whether the lights are on or off during sleep.
When a doctor refers a patient for a sleep study, the patient should ensure that the sleep center and specialist is qualified to treat the suspected problem. Sleep centers may be accredited by the American Academy of Sleep Medicine and sleep specialists may be certified by the American Board of Sleep Medicine.