March 3, 2011 -- About a third of adults in the U.S. may be getting less than seven hours of sleep per day, putting themselves at risk for serious health problems, according to two new CDC studies.
Both studies are published in the CDC’s Morbidity and Mortality Weekly Report for March 4, 2011.
In the first study, based on 2009 data from 74,571 adults in 12 states, 35.3% of adults reported getting less than seven hours of sleep in an average 24-hour period. The National Sleep Foundation recommends seven to nine hours of sleep per day for healthy adults.
Among the key findings:
- 4.7% of respondents say they had fallen asleep while driving at least once in the past 30 days.
- 7.3% of people who got less than seven hours of sleep report nodding off at the wheel, compared to 3% who got more.
- 37.9% of those questioned said they had fallen asleep unintentionally during the day at least one time in the past month.
- Of those who fell asleep unintentionally, though not while driving, 46.2% got less than seven hours of sleep, compared to 33.2% who got more.
- 48% of those surveyed said they snored. Snoring also was reported more by people who got less than seven hours of sleep.
Falling Asleep at the Wheel
Nodding off while driving apparently varies by age. Among people aged 65 or older, only 2% said they had fallen asleep at the wheel in the previous 30 days. But 3.1% of people ages 55 to 64 acknowledged nodding off while driving, compared to 3.9% for those 45-54. The study says 7.2% of adults 25 to 34 admitted falling asleep off while driving, the highest percentage of any age group.
Also, of the total sample, 5.8% of men said they nodded off while driving, compared to 3.5% of women.
“Drowsy driving, one of the most lethal consequences of inadequate sleep, has been responsible for an estimated 1,550 fatalities and 40,000 non-fatal injuries annually in the U.S.,” according to the authors of the first study. “Sleepiness reduces vigilance while driving, slowing reaction time and leading to deficits in information processing, which can result in crashes.”
Sleep Varies by Age
Older people apparently get more sleep, the study also indicates. Only 25% of people 65 and over said they slept less than seven hours in a day. In contrast, 31% of people 18 to 24 reported sleeping less than seven hours in a 24-hour period.
Sleep time also seems affected by educational level, ethnicity, race, and employment status, the statistics suggest. For example:
- 48.3% of African-Americans got less than seven hours of sleep, compared to 34.9% of whites and 33% of Hispanics.
- 37.4% of employed adults got less than seven hours of sleep, compared to 35.1%% of unemployed people.
- 39.1% of people who said they were divorced, widowed, or separated got less than seven hours, compared to 35.1% of married folks.
Findings varied widely among the 12 states studied. For instance, 27.6% of people in Minnesota reported getting less than seven hours of sleep compared to 44% in Hawaii.
Impact of Shortened Sleep on Daily Activities
The second study, based on a different set of data, examined correlations between hours of sleep and six sleep-related issues: concentrating, remembering, working on a hobby, driving or taking public transportation, taking care of finances, and working.
Trouble concentrating apparently is the biggest problem for those adults getting less than seven hours of sleep. Specifically, 19.4% of people who slept seven to nine hours a day reported trouble concentrating, but 29.3% of those sleeping less than seven had concentration problems.
Among other findings:
- 28.2% had trouble concentrating because they were sleepy or tired.
- 18.2% had trouble remembering things.
- 10.5% had trouble taking care of their financial affairs due to lack of sleep.
- Young people are more likely than those 60 and older to report having problems in all six sleep-related areas.
The researchers conclude that the perceived difficulty of performing routine daily tasks may be as much as 50% greater among adults who sleep less than seven hours.