CHICAGO, July 6 (UPI) -- A University of Chicago study has found prosperous white women get a better night's sleep than other ethnic groups.
But the study says no one gets as much sleep as they believe, the Chicago Sun-Times reports.
"People are sleeping less than they think they are -- and less than most people think is needed," said Diane Lauderdale, the school's professor of health studies.
Lauderdale and her team examined the sleep of 669 adults between 38 and 50 years old. The findings appear in the July issue of the American Journal of Epidemiology.
The study found people spend an average of 7.5 hours in bed trying to sleep but only 6.1 hours sleeping -- a sleep efficiency rate of 81 percent.
The study said white women averaged 6.7 hours of sleep per night, out of 7.8 hours spent in bed. White men got 6.09 hours of sleep. Blacks fared worse, with women getting 5.9 hours of sleep and men getting 5.1 hours, the newspaper reported.
Lauderdale said the racial gap was surprising as there is no scientific explanation for it.