People who drive commercial vehicles, such as buses, taxis, trucks and airplanes, could be incorrectly reporting their symptoms of sleep apnea due to their fears of endangering their employment, according to a new study.

The research will be presented on 1 September 2012 at the European Respiratory Society's (ERS) Annual Congress in Vienna.

People with the sleep apnea suffer frequent disruptions to their breathing during sleep, leaving them with headaches, drowsiness and sometimes depression during the day. Obstructive sleep apnea is a well-established risk for traffic accidents and commercial vehicle drivers could lose their license if their illness is perceived to be compromising safety while driving.

The regular treatment for sleep apnea is continuous positive airway pressure (CPAP), which uses a mask and other equipment to generate a stream of air to keep the upper airway open during sleep. As commercial drivers regularly do shift work, they don't follow regular patterns of sleep and also do not always sleep in one place; this makes adherence to CPAP treatment more difficult.

Researchers examined 37 commercial vehicle drivers with sleep apnea and compared them with a control group of 74 patients. Both groups had similar characteristics of age, body mass index (BMI) and similar numbers of disturbances suffered on average during the night. Both groups also underwent treatment using CPAP.

Levels of sleepiness were then analyzed using the Epworth Sleepiness Score; a well-established short questionnaire used to give levels of sleepiness during the day time. The survey provides a score, which is the sum of 8 items and can range between 0 and 24.The higher the score, the higher the person's level of daytime sleepiness

At the start of the study, commercial drivers reported an average score of 8.1 on the sleepiness scale, compared with an average of 11.0 reported by non-commercial drivers, despite a similar number of disturbances at night between the two groups. The difference was also seen after 6 months of treatment using CPAP therapy with the drivers reporting an average sleepiness score of 4.8 and non-drivers reporting an average of 7.7.

The results also showed that drivers received less treatment (only receiving CPAP for an average of 75% of days, compared with 83%) and also had more unscheduled visits to the clinic, which suggests they were struggling with their symptoms.

The authors speculate that the lower scores reported by the commercial drivers could be due to drivers under-scoring their sleepiness levels for fear of losing their license permissions.

Lead author, Dr. Werner Strobel from University Hospital, Switzerland, said: "Our study suggests that commercial drivers are playing down their levels of sleepiness for fear of losing their jobs. Although this is very difficult to prove, both the group of drivers and the group of non-drivers began the study with a similar number of disturbances during the night. You would therefore expect their reports of sleepiness to be similar to begin with, however the drivers estimated their levels of sleepiness as lower than the non-drivers. This pattern continued throughout the course of the study, with drivers reporting lower symptoms, yet receiving less treatment and making more unscheduled visits to the clinic.

"We can assume from these results that commercial drivers with sleep apnea symptoms could be under-reporting their sleepiness in order to protect their job. These results should be taken into account by healthcare professionals who are treating this group of people."

Dan Smyth from the Irish Sleep apnea Trust, said: "We know that an above average number of people involved in commercial driving have sleep apnea. It is also known that many of them, mainly through ignorance of the condition and fear of losing their livelihood, are afraid to report it to their employer or seek help. The findings of this study confirm the current situation and show further evidence that Relative Advocacy and Support Groups, with the support of our legislators, must deliver a positive message on the benefits of treating Sleep apnea to the Transport Industry."

Abstracts from the ERS Congress will be publicly available online August 26, 2012.