Dr. Maple M. Fung of the San Diego Veterans Affairs Healthcare System, Medicine Service, and colleagues contacted participants from the Outcomes in Sleep Disorders in Older Men Study and 784 of those subjects met criteria for the study, CardiologyToday.com reports.
The mean age of participants was 75. They answered questionnaires focusing on participant demographics -- including race, lifestyle factors and medications -- and participants' height, weight, body mass index and waist, hip and neck circumferences were all recorded by researchers.
At the time of the initial study, participants had two seated resting blood pressure measurements taken. In a follow-up visit, participant blood pressure was taken again.
"In-home, single-night sleep studies using unattended polysomnography -- diagnostic tool in sleep medicine -- were performed" to record rapid eye movement sleep and non-rapid eye movement sleep stages and slow-wave sleep.
The study, published in the journal Hypertension, finds after a mean follow-up of 3.4 years, 243 of the 784 participants met criteria for hypertension -- but after factoring for age, non-white race, study site and body mass index, only slow-wave sleep showed a significant and inverse association with incident hypertension.
Fung owns stock and is an employee at Amgen, an international biotechnology company headquartered in Thousand Oaks, Calif.