By Leslie Mann, Special to the Tribune
July 25, 2012
The average amount of time people sleep each night varies from race to race, according to a study of 500 Chicago-area adults by Northwestern Medicine in Chicago.
Whites sleep the most, followed by Asians and Hispanics. Blacks sleep the least.
The study also said that blacks have the worst quality of sleep, while Asians have the highest amount of daytime sleepiness.
The study is more accurate than its predecessors, said Mercedes Carnethon, associate professor of preventive medicine at Northwestern University Feinberg School of Medicine, because it used randomly selected participants whose sleep was tracked by wrist monitors instead of self-reporting.
Race is a factor, said the study, despite gender, age, education level and whether or not the participants had cardiovascular disease risk or depressive symptoms (depression or anxiety).
The average length of nighttime sleep was 7.4 hours for whites, 6.9 for Asians and Hispanics and 6.8 for blacks.
The study excluded people with sleep disorders.
The monitors recorded movement associated with sleeping. Participants wore them for seven days.
Carnethon's to-do list includes following the participants from this study long-term and conducting additional studies that weigh other demographic variables such as type of housing, neighborhood density, household size, marital status, job stress and income.
"This has public health implications," said Carnethon. "Depending on where people of different races live, they are affected by things like ambulance sirens, public transit schedules and outdoor lighting."
Americans get less sleep than they did 10 years ago, said Carnethon, although there is scant credible data before that.
"Dual careers, more stress, longer working hours, irregular bed times — these all affect our sleep," she said.
Sleep deprivation can cause delayed reaction time, which can cause car accidents. It affects metabolism and eating patterns, which can lead to obesity and other health problems.
Adults should get seven to nine hours of sleep each night, said Carnethon, "but it tends to lessen as we age."
Adolescents should get eight to nine hours, while pregnant women should get nine to 10.
"If a healthy adult sleeps more than nine hours a night, it may indicate a health problem," she said.
People can increase their sleep time, said Carnethon, by going to bed at the same time each night and avoiding "screen time" with computers and televisions right before they go to bed.
"Yes, you can catch up on sleep on weekends and rebound if you get too little sleep during the week," she said. "But do we really want a truck driver operating on three hours a night?"
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