Relationship between daytime sleepiness and blood pressure in healthy older adults

Background: Some sleep disorders have been linked to hypertension, but few studies have examined the relationship between daytime sleepiness and blood pressure (BP). This study attempted to determine whether scores on a short questionnaire assessing daytime sleepiness (Epworth Sleepiness Scale [ESS]) were associated with BP and could be used to predict hypertension after 5 years in healthy older adults who had not previously been diagnosed with hypertension. Methods: A group of 157 healthy men and women 55 to 80 years of age completed an extensive medical examination, a series of psychosocial tests, and two 24-h ambulatory BP sessions. After 5 years the procedures were repeated in 133 (85%) of the subjects. Psychosocial variables and BP were compared in subjects scoring high (score of 10) and low (10) on the ESS. Results: Compared to individuals with low ESS sores, those scoring high had increased casual and sleep BP as well as higher systolic BP levels and diastolic BP variability during waking hours, and reported higher levels of anger, depression, anxiety, and intensity of psychological symptoms as well as lower defensiveness. Individuals with high ESS scores were more likely to be diagnosed with hypertension 5 years later. Groups with high and low ESS scores did not differ significantly on any other variables. Conclusions: The ESS, a simple measure of daytime sleepiness, identified individuals at risk for hypertension. Future studies should investigate the possibility that diagnosis and treatment of daytime sleepiness could aid in BP reduction and ultimately in decreased morbidity and mortality from cardiovascular disorders. Am J Hypertens 2004;17:787–792 © 2004 American Journal of Hypertension, Ltd

Scale Invariance and Nonlinear Patterns of Human Activity

We investigate if known extrinsic and intrinsic factors fully account for the complex features observed in recordings of human activity as measured from forearm motion in subjects undergoing their regular daily routine. We demonstrate that the apparently random forearm motion possesses previously unrecognized dynamic patterns characterized by fractal and nonlinear dynamics. These patterns are unaffected by changes in the average activity level, and persist when the same subjects undergo time-isolation laboratory experiments designed to account for the circadian phase and to control the known extrinsic factors. We attribute these patterns to a novel intrinsic multi-scale dynamic regulation of human activity.Comment: 4 pages, three figure