Breathing problems during sleep appear to affect blood pressure in shift workers 40 years of age or older, according to findings published in the American Journal of Hypertension.Sleep-disordered breathing describes a group of disorders affecting breathing during sleep. The most common type is obstructive sleep apnea, in which the back of the throat collapses periodically during sleep, and breathing stops for a few moments until the patient wakens enough to resume breathing. Because the patients aren't getting a good night's rest, they often feel sleepy during the day with sluggish mental performance."Sleep-disordered breathing can be one of the major determinants of high blood pressure, but there has been no study on sleep-disordered breathing with an emphasis on shift workers," Dr. Takeshi Tanigawa, of the University of Tsukuba, Japan, and colleagues write.In a new study, the Tanigawa's team of researchers examined the association between blood pressure and sleep-disordered breathing among shift workers and day workers in a Japanese nuclear power plant. Blood pressure levels and oxygen desaturation, which is used to assess the extent of sleep-disordered breathing, were measured among 253 male shift workers and 206 male day workers between the ages of 30 and 62 years.The rate of sleep-disordered breathing occurring at least 10 and at least 15 times per hour was 11.3 and 6.1 percent, respectively. There were no significant differences between shift and day workers.As noted, sleep-disordered breathing was linked to higher blood pressure levels, primarily in older shift workers, the authors state. "The relationship between sleep-disordered breathing and (high blood pressure) is more complicated than we thought, and work schedules need to be taken into account in both studying and treating (high blood pressure) and sleep apnea."