On Oct. 20, the National Transportation Safety Board (NTSB) sent a letter to the Federal Motor Carrier Safety Administration and the U.S. Coast Guard recommending they evaluate commercial vehicle drivers and mariners for obstructive sleep apnea (OSA) and treat them if need be.

OSA occurs when the airway becomes blocked during sleep, completely or partially, said Shahnaz Motamedi, a nurse practitioner for NNMC’s Sleep Disorder Center. When oxygen saturation drops, the lack of oxygen to the brain forces the brain to send signals to the body ordering it to clear the blockage, thus triggering a gasp of air that reopens the airway.

‘‘These episodes can occur repeatedly throughout the night,” Motamedi said. ‘‘They may last a few seconds to minutes, consequently interrupting a person’s sleep.”

Some signs that a person is suffering from sleep apnea include excessive fatigue, excessive sleepiness, mood swings and irritability, she said.

Sleep apnea has been an ongoing concern over the years and has been linked to various traffic accidents in recent years, said Terry Williams, a NTSB spokesperson. In the Board’s recent letter, NTSB cited several transportation accidents involving sleep apnea, including the 2007 Cosco Busan crash that led to an oil spill in the San Francisco Bay.

The letter also cited a 2002 review of the epidemiology of obstructive sleep apnea estimated roughly seven percent of adults have at least moderate OSA.

OSA is fairly common, Motamedi said, with an estimated 18 million Americans with the disorder.

Some of the major contributing factors include age, weight, family history and being male, Motamedi said.

‘‘The good news is that OSA can be treated 100 percent with the use of a continuous positive air pressure (CPAP). The machine forces the air through the airway to keep it open,” she said.

Treatment options include oral appliances, which help bring the jaw forward to keep the airway open, and surgery, she said.

When left untreated, sleep apnea has been known to cause other major health problems such as hypertension, cardiovascular disease, diabetes and depression, Motamedi said.

‘‘A healthy lifestyle should encompass not only plenty of exercise and a balanced diet, but also adequate sleep,” she said. ‘‘Sleep deprivation and OSA alters learning and memory functions and also inhibits one’s ability to lose weight ... If you don’t have good sleep, it’s going to affect your performance, alertness and your immune system ... all of our daily living activities.”