The researchers think the growing national problems with diet, obesity and sedentary lifestyles are largely to blame for the increase.The study appeared this week in the online version of the journal Epidemiology and will be in the print edition. Researchers tested more than 14,000 people between the ages of 24 and 32 and found that nearly 1 in 5 had high blood pressure nearly five times the rate found in an earlier study.High blood pressure, also called hypertension, is a factor in heart disease and strokes, the top and thirdranked leading causes of death among Americans, respectively. She called the findings evidence of a sleeping epidemic."We tend to think of young adults are rather healthy, but a prevalence of 19 percent with high blood pressure is alarming, especially since more than half did not know that they had high blood pressure," she said.The data for the report were derived from the larger National Longitudinal Study of Adolescent Health, that has been track