Neck Size, BMI and your CDL. Drivers Beware You Might Be OOS Soon.


Ready to get your Medical Card updated?  Feeling healthy, and you cruised through your last exam? What’s to worry about?  Plenty.

If your neck is bigger than 17 inches, or your BMI is 35 or greater, there might be a medical “out of service” in your future.  So let’s see how this can happen, what you need to worry about, and then in conclusion, what you can do to prevent an out of service.  Remember over 40% of drivers will meet one of these “criteria”.


The DOT does, and through regulations being promulgated by the FMCSA, DOT is going to have your neck size and body mass measured.  Turns out there is a statistical correlation between your neck size and / or your body mass index, and the likelihood of sleep apnea.

According to the National Institute of Health;

Sleep apnea (AP-ne-ah) is a common disorder in which you have one or more pauses in breathing or shallow breaths while you sleep.

Breathing pauses can last from a few seconds to minutes. They may occur 30 times or more an hour. Typically, normal breathing then starts again, sometimes with a loud snort or choking sound.

Sleep apnea usually is a chronic (ongoing) condition that disrupts your sleep. When your breathing pauses or becomes shallow, you’ll often move out of deep sleep and into light sleep.

As a result, the quality of your sleep is poor, which makes you tired during the day. Sleep apnea is a leading cause of excessive daytime sleepiness.

Sleep apnea often goes undiagnosed. Doctors usually can’t detect the condition during routine office visits. Also, no blood test can help diagnose the condition.

This last part is most important, to reiterate, “sleep apnea often goes undiagnosed“.  Thus, the DOT is trying to find a way to flag CDL drivers who “might” have sleep apnea for further screening.  This is where neck size and the Body Mass Index (BMI) come into play.

According to WebMd;

More than half of people with obstructive sleep apnea are either overweight or obese, which is defined as a body mass index (BMI) of 25-29.9 or 30.0 or above, respectively. In adults, excess weight is the strongest risk factor associated with obstructive sleep apnea.

Each unit increase in BMI is associated with a 14% increased risk of developing sleep apnea, and a 10% weight gain increases the odds of developing moderate or severe obstructive sleep apnea by six times. Compared to normal-weight adults, those who are obese have a sevenfold increased risk of developing obstructive sleep apnea. But the impact of BMI on obstructive sleep apnea becomes less significant after age 60.

BMI isn’t the sole marker of obesity that’s important. Men with a neck circumference above 17 inches (43 centimeters) and women with a neck circumference above 15 inches (38 centimeters) also have a significantly increased risk of developing obstructive sleep apnea.

So as you will see, DOT is trying to screen CDL drivers by requiring doctors doing medical certifications to flag anyone with a large neck or high BMI for further testing of sleep apnea.

According to The Medical Examiner’s Handbook produced by the FMCSA:

Treatments for OSA [obstructive sleep apnea] include surgery and continuous positive airway pressure (CPAP). The successfully treated driver may be considered for certification following the recommended waiting period. You should not certify the driver with suspected or untreated sleep apnea until etiology is confirmed and treatment has been shown to be stable, safe, and adequate/effective.

Waiting period

Minimum — 1 month after starting CPAP

Minimum — 3 months symptom free after surgical treatment

NOTE: If more than one waiting period applies (because of multiple conditions or other comorbid diseases), examine the driver for certification after the completion of the longest waiting period.


Maximum certification — 1 year

Recommend to certify if:

The driver has:

  • Successful nonsurgical therapy with:
    • Multiple sleep latency testing values within the normal range.
    • Resolution of apneas confirmed by repeated sleep study during treatment.
  • Continuous successful nonsurgical therapy for 1 month.
  • Compliance with continuing nonsurgical therapy.
  • Resolution of symptoms following completion of post-surgical waiting period.

Recommend not to certify if:

The driver has:

  • Hypoxemia at rest.
  • Diagnosis of:
    • Untreated symptomatic OSA.
    • Narcolepsy.
    • Primary (idiopathic) alveolar hypoventilation syndrome.
    • Idiopathic central nervous system hypersomnolence.
    • Restless leg syndrome associated with EDS.


The driver who is being treated for sleep apnea should remain symptom free and agree to:


  • Continue uninterrupted therapy.


  • Undergo yearly objective testing (e.g., multiple sleep latency test or maintenance of wakefulness test). See Sleep Disorder Tests.According to;


    The current DOT regulations include BMI and neck size as key indicators for sleep apnea that medical examiners will be looking for during recertification physical exams. The DOT currently wants anyone with a BMI of 35 or greater to have a sleep study performed as well as anyone with a neck size of 17 inches or greater (for males) and 16 inches or greater (for females) to have a sleep study done. Drivers whose sleep study results are positive for sleep apnea and who have been set up on CPAP treatment, will have to meet certain compliance requirements when using their CPAP machines. To meet current DOT regulations, CDL holders must use their machines for 70% of the week which roughly equates to 4 hours a night for 5 nights a week.

    The Federal Motor Carrier Safety Administration’s (FMCSA) goal is to reduce commercial vehicle related fatalities and injuries. A FMCSA study found is that an estimated 28% of Commercial driver’s license (CDL) holders suffered from some form of sleep apnea ranging from mild (17.6%), to moderate (5.8%) to severe (4.7%).



Well summarizing, if you have a BMI above 35 or a neck above 17 inches for a male, or 16 inches for a female, the DOT registered Medical Examiner “has” to test you for Sleep Apnea.  The definitive test is a sleep study, which is essentially an overnight visit, that can’ be done on the spur of the moment, and if you are unlucky enough to “fail” only a month of successful treatment (best case scenario) will ensure your Medical Card is issued.

Even worse, Overdrive Magazine has reported that:

Drivers who walk in to a medical examiners office with any of the above will be told they need to be tested for sleep apnea, McDermand said, and he’s hearing frequently from drivers who say the examiners aren’t renewing med cards if they haven’t been tested.

So drivers need to be proactive.  If your BMI is above 35 (Calculate your BMI here) or your neck is over 17 inches (16 for woman), you should get a sleep study at least three months before your Medical re-certification is required.  Because if you test positive for sleep apnea you will have time to get treatment and prove the treatment was effective at the time of re-certification.

Unfortunately this is the new reality of regulation in truck driving.  CDL drivers need to be vigilant, both when they drive and when they negotiate the maze of regulations inherent to the industry.   Make sure you pass this information along to fellow drivers,  as a medical out of service can break most peoples finances.  They’ll be sure to thank you.


Yes they did, forbidding any new guidance on sleep disorders, and requiring FMCSA to use the rule making process only.  But the net effect is not to stop this issue of BMI and neck size from interfering with your medical certification.

“Rulemaking will take at least two and possibly four years on a contentious topic like sleep apnea. In the meantime the “no rule – rule” of informal guidance to medical examiners will be in place. This informal guidance is that all drivers with a Body Mass Index (BMI) over 35 be required to get tested for sleep apnea. If positive for OSA, treatment with a Continuous Positive Airway Pressure (CPAP) machine would be required for DOT medical certification.” –


Since there is no FMCSA regulation regarding sleep apnea evaluation and the basic parameters are subject to interpretation, then be aware of the Medical Examiner’s position.

  • The medical examiner’s job is not to diagnose. It is to assess the driver’s medical fitness to determine if any safety risk issues exist.
  • If there is a reasonable chance of risk then the examiner will request that a specialist in that field provide a proper diagnosis and treatment if necessary.
  • If you’ve been diagnosed with sleep apnea, then another set of regulations apply.

By being proactive, you get to manage this before it becomes an issue. –

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