A new study finds that reduced slow wave sleep (SWS) is a good predictor for developing high blood pressure in older men. Researchers from the Outcomes of Sleep Disorders in Older Men Study (MrOs Sleep Study) found that people with the lowest level of SWS had an 80% increased risk of developing high blood pressure.

Men who spent less than 4% of their sleep time in SWS were significantly more likely to develop high blood pressure during the 3.4 years of the study. Furthermore, men with reduced SWS had generally poorer sleep quality as measured by shorter sleep duration and more awakenings at night and had more severe sleep apnea than men with higher levels of SWS. However, of all the measures of sleep quality, decreased SWS was the most strongly associated with the development of high blood pressure. This relationship was observed even after considering other aspects of sleep quality, according to the researchers.

While the participants’ average body mass index was 26.4 kg/m2, the researchers point out that the study effects of SWS were independent of obesity and continued to be seen after considering the effects of obesity.

The researchers evaluated 784 men, who did not have hypertension, in their own homes using standardized in-home sleep studies, or polysomnography, with measurement of brain wave activity distinguishing between REM and non-REM sleep, and sleep apnea through measurement of breathing disturbances and level of oxygenation during sleep. Participants were an average of 75 years old and almost 90% were Caucasian. Among sleep disturbance measurements, researchers assessed frequency of breathing disturbances, time in each sleep state, number of nighttime awakenings, and sleep duration.

Generally, older men and women are more likely to develop high blood pressure than younger people. Sleep disorders and poor sleep quality are similarly more common in older adults than in younger ones.

In the Sleep Heart Health Study, another large cohort study, researchers found that men were more likely to have less SWS than women. Men were also at an increased risk of high blood pressure when compared to women. The current study, according to the researchers, raises the possibility that poorer sleep in men may partly explain the male gender predisposition to high blood pressure.

The findings appear in Hypertension: Journal of the American Heart Association.