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Up to 70 million Americans have a sleep disorder: persistent difficulty sleeping and subsequent trouble functioning during the day. More than 40 million don’t get a proper diagnosis or treatment, according to research published in the journal Sleep Medicine.

Some people may be unaware of sleep interruptions, and often “patients don’t bring their sleep to the attention of doctors because they don’t think it’s ‘medical’ or think they should tough it out,” says Matt T. Bianchi, director of the sleep division at Massachusetts General Hospital in Boston.

Past surveys have shown that medical schools have formally devoted, on average, less than two hours to sleep medicine, and doctors may not routinely discuss it at office visits. A study in the Journal of Clinical Sleep Medicine found that only 25 percent of primary-care providers asked new patients about sleep, although many had signs of problems. Doctors might also find it hard to pinpoint which of the 60 sleep disorders is the culprit because symptoms may be unclear and because other illnesses and habits may affect rest.

If you often have trouble falling or staying asleep, or if you can’t function normally as a result of that difficulty, your doctor can help rule out illnesses that can affect sleep, such as depression and overactive thyroid, and might be able to zero in on the cause. In tougher cases, a board-certified sleep specialist can conduct a detailed evaluation.

Here’s how three common sleep disorders are evaluated:

Chronic insomnia

This affects about 10 to 15 percent of adults and is defined as trouble falling or staying asleep at least three times per week for three months or longer.

Your doctor will ask about symptoms and their effects — whether, for example, your partner says you snore. He or she will also ask lifestyle questions and try to identify whether habits such as heavy caffeine or alcohol consumption, use of electronic devices close to bedtime or medications may be contributing.

If your doctor can’t get to the root of the problem, see a sleep medicine physician. This specialist might have you keep a diary of sleep, exercise and food and alcohol intake, and may order actigraphy testing, which helps track your sleep with a wristwatchlike device. If a sleep-disrupting problem is suspected, an overnight sleep lab polysomnogram may be in order. Here, as you sleep, electrodes record your brain waves, heartbeat, breathing, eye movements and blood-oxygen levels. Sensors measure chest movement and the strength and duration of your breaths.

Obstructive sleep apnea

Obstructive sleep apnea, or OSA, which is characterized by numerous brief pauses in breathing during sleep, can cause significant daytime sleepiness. Sufferers may also fall asleep at inappropriate times.

An estimated 25 million Americans have this condition, with 12 million to 18 million undiagnosed. And research published in the Journal of Clinical Sleep Medicine suggests that OCA may often be misdiagnosed as depression.

To properly diagnose OSA, you’ll need a sleep lab polysomnogram or an overnight home sleep apnea test, where electrodes record breathing and heart rate, blood-oxygen levels and chest movements. This may not detect mild apnea and is prone to false negatives, so if results are negative but your doctor strongly suspects apnea, you’ll need a polysomnogram.

Restless legs syndrome

RLS, which affects about 10 percent of American adults, causes leg sensations such as burning, a creepy-crawly feeling, throbbing and an uncontrollable urge to move your lower limbs. That can make it hard to fall asleep, and it can wake you up.

Doctors might mistake RLS for conditions such as anxiety, arthritis, back injury and poor circulation. It can also mimic diabetic neuropathy. In one study, 81 percent of people with RLS reported symptoms to their doctor, but just 6 percent received proper diagnoses.

You don’t need a polysomnogram to diagnose RLS unless your doctor can’t pinpoint which sleep disorder you have. A symptom history and exam should be enough, says the American Academy of Sleep Medicine.

Copyright 2016. Consumers Union of United States Inc.

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