Sleep should be the great equalizer. Whatever differences might divide us during the day, the nonconsciousness that comes with nighttime should be one thing we all have in common.

It ain't necessarily so. Scientists have now found significant differences exist in how people sleep in the U.S. depending on race, ethnicity and country of origin, suggesting genetic or cultural differences in shut-eye patterns. This line of research could help identify how these disparities might affect health and find better ways to improve sleep.

One study looked at sleep data gathered from more than 430,000 people in the U.S. between 2004 and 2010 as part of the National Health Interview Surveys, which the U.S. Centers for Disease Control and Prevention conducts annually to monitor the country's well-being. They found that foreign-born respondents were generally more likely to sleep the recommended healthy six to eight hours each night as compared with native-born Americans.

"This study is particularly interesting, because it goes to show that the unhealthy American lifestyle includes more than a poor diet and lack of exercise—it also means unhealthy sleep patterns, and this can lead to important health consequences," says sleep researcher Michael Grandner at the University of Pennsylvania, who did not take part in this research. "It seems like foreign-born Americans may be protected by not adopting this unhealthy lifestyle."

Past research suggests that habitually sleeping less or more than the recommended six to eight hours for adults can be linked to certain higher health risks, such as cardiovascular disease, diabetes, obesity, stroke, cancer and accidents as well as instances of mental disorders such as depression. These findings regarding sleep disparities "can help us understand not only who to target for improving sleep with the aim of improving health, but it can help us identify the social and environmental influences on sleep, which might be modifiable," Grandner says. Unlike many other foreign-born persons, African-born Americans were more likely to report sleeping six hours or less, suggesting that helping them find more sleep could help them with other health issues, says the study's lead author Abhishek Pandey, a sleep researcher at the State University of New York Downstate Medical Center.

Another study analyzed 439 volunteers in the Chicago Area Sleep Study, a randomly selected, racially diverse sample of Chicago adults who donned wrist sensors that measured how long they slept each night for a week and answered surveys about sleep quality and daytime drowsiness. Researchers found that white participants on average slept about 30 minutes longer than other ethnic groups whereas blacks reported the worst sleep quality and Asians claimed to be the most sleepy during the day.

These disparities apparently represent normal experiences, and not underlying sleep disorders, says the study's lead author Mercedes Carnethon, an epidemiologist at Northwestern University. For instance, these differences persisted even after statistically adjusting for cardiovascular disease risk factors that researchers already know are linked with poor sleep, such as body mass index, high blood pressure and diabetes. The scientists also excluded people who had evidence of mild to moderate sleep apnea, a disorder that causes abnormal pauses in breathing during sleep.

"These studies show very clearly that when, how and how much you sleep is partially determined by who you are and where you come from," Grandner says. Pandey, Carnethon and their colleagues detailed their findings June 13 at the annual meeting of the Associated Professional Sleep Societies in Boston.

Differences in sleep patterns might stem from genetic and anatomical variations between groups. For instance, past research suggests blacks and whites might sleep differently because of disparities in inflammation responses and that various groups might display distinctive the structure in their airways, influencing how they breathe during sleep, Pandey says.

9 Comments

1. 1. curmudgeon 10:45 AM 6/18/12

   "Unlike many other foreign-born persons, African-born Americans were more likely to report sleeping six hours or less, suggesting that helping them find more sleep could help them with other health issues"
   
   This seems like an awfully big leap even for the Big Brother Nanny. If variations in sleep patterns are indeed genetic why does this not lead one to suppose that they are probably best left alone to find their own natural rhythm? As the study itself shows there is no universal 'norm' for sleep and therefore, like every other 'healthy living' standard (how much alcohol you should drink, how many portions of vegetables we need etc. etc.) this would be nothing but a wild guess!

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2. 2. LarryW 03:36 PM 6/18/12

   The sleep studies need to be broadened be international in scope and more controlled. Any sleep study must take into account culture and ethnicity, work habits and life habits, etc. For example, the language above suggested the study looked at sleep at night. But many cultures have afternoon "siestas", eat at different hours of the day, etc.
   
   The assumption from the first paragraph that we should have night time sleep in common would have never occurred to me.

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3. 3. ssm1959 04:08 PM 6/18/12

   Chronic sleep deprivation is potentially the 800 pound gorilla of healthcare. It is an area chronically overlooked by physicians, even in patients that are suffering from conditions know to originate or exacerbate due to sleep deprivation. A UCLA study many years back looked at hypertension in compliant patients. The cases were reviewed by a panel and determined to be individuals that even with the highest compliance would always be dependent on drug management. The researchers then took the subjects to a compound where the controlled everything from diet to exercise and sleep cycle. In 4 weeks 90% of the patients had normalized blood pressures without medication. Granted the ate are a lot of variables her to assign significance to any one. It still makes a powerful statement of how important it is to get patients to focus on getting closer to normal in these parameters, particularly sleep.

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4. 4. jgrosay 04:30 PM 6/18/12

   Is this information pointing towards a positive effect of jet-lag?

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5. 5. marclevesque 04:49 PM 6/18/12

   Could you please provide links to, or titles of, the studies so they will be easier to find

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6. 6. medlibman 03:50 PM 6/20/12

   I came across this article recently, and found it very interesting in the context of how we ordinarily think of "a good night's sleep" nowadays.
   
   Broken Sleep May Be Natural Sleep
   http://www.psychiatrictimes.com/display/article/10168/55271

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7. 7. jackvandijk 06:44 PM 6/20/12

   Sleep is dependent on how secure and safe you feel you are. In the US you are not safe.

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8. 8. bucketofsquid in reply to jackvandijk 05:06 PM 6/25/12

   We are safer in the USA than people in almost the entire rest of the world are. I imagine that Finland is fairly safe to live in during the summer. I haven't seen crime statistics for Iceland either so that country may be safe. Just remember that crimes and crime rates aren't the same and areas with ongoing revolutions or domestic unrest are also dangerous.

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9. 9. jackvandijk in reply to bucketofsquid 11:41 AM 6/26/12

   to bucketofsquid
   The USA has proportionally and absolute the largest incarcerate population (prisoners), a large majority of whom are black. Nevertheless I am much safer in the European countries.

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