The condition can cause people to fall asleep behind the wheel or while operating machinery.

By Amanda MacMillan
Updated September 22, 2017

Two commuter train crashes in the New York City metropolitan area are being blamed on undiagnosed sleep apnea, according to an announcement yesterday from the National Transportation Safety Board. Investigations have determined that the conductors in both accidents—a September 2016 New Jersey Transit crash in Hoboken, New Jersey, that killed one person and a January 2017 Long Island Railroad derailment in Brooklyn that injured more than 100—fell asleep on the job due to the chronic condition.

Sleep apnea is a very common condition, and it’s easy for doctors to spot, says Allan Pack, MD, professor of medicine at the University of Pennsylvania’s Center for Sleep and Circadian Neurobiology. (Dr. Pack was not involved in the investigations above, and has not evaluated the train conductors.)

But even though knowledge about the condition is growing, says Dr. Pack, many people don’t realize they have a problem—and so it frequently goes undiagnosed and untreated. Here’s what he wants people to know about sleep apnea.

It affects your breathing while you sleep

“Obstructive sleep apnea is a condition in which your airway closes during sleep,” says Dr. Pack. “When you’re awake, the muscles in your airway are active—but when you sleep and those muscles collapse, in some people the airway narrows or becomes blocked completely.”

This keeps oxygen from circulating throughout the body, and causes carbon dioxide levels to build up instead. “When the brain senses that, it wakes you into a lighter stage of sleep,” says Dr. Pack. “It sends a signal to those muscles and reopens the airway so you can breathe—but the problem is you’re getting interrupted all night long and not able to get into the deeper stages of sleep.”

Some people with sleep apnea will notice that they’re waking up all night long, but they may not understand why. Others will never fully wake up, and think they’re sleeping soundly all through the night but wonder why they don’t feel rested in the morning.

Being overweight is the biggest risk factor

Men are more likely to have sleep apnea than women; other risk factors include being older, being a smoker, drinking alcohol or using sedatives, and having a thick neck and/or narrow airways. But the biggest risk factor for men and women of all ages, Dr. Pack says, is being overweight.

"If you’re overweight, you’re more likely to have excess fat deposited in the upper airway,” he says. Because of that, as the country’s obesity epidemic is growing, the rates of sleep apnea are increasing as well.

Symptoms include snoring, headaches, and fatigue during the day

Spouses or bed partners are usually the first ones to know if a person has sleep apnea, because they will hear him or her snoring loudly throughout the night—a sign that air is not flowing smoothly through the airway as it should. Sometimes, they will even notice that their partner stops breathing for a few seconds, before gasping or snorting and falling back into a normal rhythm.

People with sleep apnea may not be aware themselves that this is going on at night, but they’re likely to feel tired when they wake up. They may also suffer unexplained headaches, irritability, and memory problems, and may find themselves nodding off throughout the day.

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These aren’t the first accidents sleep apnea has caused

One of the biggest dangers of sleep apnea—besides the fact that it raises blood pressure and increases the risk for heart disease and diabetes—is that it can put people at risk for falling asleep behind the wheel, or while operating machinery.

Sleep apnea has previously been ruled responsible for a 2013 MetroNorth train derailment that killed four people, and has likely contributed to countless automobile crashes, says Dr. Pack.

Because of that, some companies (including MetroNorth and the LIRR) have started screening train operators, truck drivers, and other employees for the condition. Last year, President Obama proposed national guidelines that would require all trucking and railroad companies to do the same, but in August the Trump administration said it would not pursue such regulations.

There’s a drug-free treatment that works extremely well

About 60% of people who are diagnosed with sleep apnea experience major improvement after beginning a treatment called continuous positive airway pressure, or CPAP, says Dr. Pack. The treatment involves wearing a mask over your nose and mouth while you sleep, which is connected to a tube that blows oxygen through the airway—holding it open while you sleep.

CPAP can take some getting used to, says Dr. Pack, and other treatments are also available if patients really can’t adapt to sleeping with the machine. “But it really is the first-line of therapy,” he says, “and for the majority of patients, once they give it a try and realize how much their sleep has improved and all of the other benefits they get from that, they love it.” He encourages anyone with sleep apnea symptoms to talk to their doctors about diagnosis and treatment—for their own safety as well as the safety of others.