Sleep in America: News From the National Sleep Foundation and the CDC

BY DR. BARBARA PHILLIPS, MSPH, FCCP

Coincident with the loss of sleep that accompanies the change to daylight savings time, the National Sleep Foundation (NSF) and the Centers for Disease Control and Prevention (CDC) released the results of their investigations of America’s sleep behaviors during National Sleep Awareness Week (March 7-12).

The National Sleep Foundation 2011 Sleep in America Poll
The NSF poll (http://www.sleepfoundation.org/article/sleep-america-polls/2011-communications-technology-use-and-sleep) focused on sleep and the use of communication technology. This poll included 1,508 surveys (about half of which were Web-based and half of which were by telephone). The respondents were between 13 and 64 years of age. The margin of error for this poll is 2.5 percentage points at the 95% confidence level. In this poll sample, the overall prevalence of sleepiness, defined as an Epworth Sleepiness Scale score (Johns. Sleep. 1991;14[6]:540) of 11 or higher, was 13%. There were striking differences by age group, with youngest people being the sleepiest. The prevalence of those with an Epworth Sleepiness Scale score of at least 11 fell from 22% in the 13 to 18 year age group to 9% in those over 46 years.

On average, the participants in the NSF poll reported needing about 7 1/2 h of sleep a night but only getting about 6 h and 55 min of sleep on weeknights. Part of the reason for this sleep gap appears to be electronic technology. Most (95%) of those surveyed use some type of electronic technology (television, computer, video game, or cell phone) at least a few nights a week within the hour before bed. There were striking (but not surprising) differences in these behaviors by age groups. Older people tended to report watching TV more, while younger people were much more likely to report cell phone texting. Cell phones were also reported to disturb sleep, with about 20% of those under the age of 30 reporting that they are awakened by a phone call, text message, or e-mail message at least a few nights a week.

About one-third (37%) of the respondents reported drowsy driving in the past month. This behavior also decreased with age; about half of the youngest (age 19 to 29) drivers reported drowsy driving at least once in the past month, but this was reported by only about 28% of baby boomers. Those who reported drowsy driving were more likely to get less sleep on weeknights, to have Epworth Sleepiness Scale scores of 11 or higher, and to be awakened by cell phones at night.

The CDC Behavioral Risk Factor Surveillance System (BRFSS) Report of Sleep Behaviors 2009
The CDC also released results during National Sleep Awareness Week of a study (McKnight-Eily et al. MMWR. March 4, 2011;60[8]) of Americans’ sleep behaviors. This report was based on the Behavioral Risk Factor Surveillance System (BFRSS). The BRFSS is a state-based, random-digit–dialed telephone survey of the US adult population. This survey has been conducted by state health departments in collaboration with the CDC for many years. Some components are compulsory and are included annually, and others may be voluntarily included by individual states. California, Georgia, Hawaii, Illinois, Kansas, Louisiana, Maryland, Minnesota, Nebraska, New York, Texas, and Wyoming included an optional sleep module in their 2009 BRFSS, and the data from that module were used to formulate this report. Response rates ranged from 40% in Maryland to 66.9% in Nebraska, and included 74,571 adults.

The questions about sleep (and instructions to the interviewer) were: “On average, how many hours of sleep do you get in a 24-h period? Think about the time you actually spend sleeping or napping, not just the amount of sleep you think you should get (categorized as less than 7 h and greater than or equal to 7 h).” “Do you snore? (can have been told by spouse or someone else; categorized as yes or no)?” “During the past 30 days, for about how many days did you find yourself unintentionally falling asleep during the day (categorized as none or at least 1 day reported)?” and “During the past 30 days, have you ever nodded off or fallen asleep, even just for a brief moment, while driving (categorized as yes or no)?”

About one-third of the respondents (35.3%) reported sleeping less than 7 h on average during a 24-h period. The highest rate of this behavior was in Hawaii (44.6%), and the lowest was Minnesota in (27.6%). People who were at least 65 years old were significantly less likely to report sleeping less than 7 h (24.5%) than persons in any other age categories. Non-Hispanic blacks (48.3%) and non-Hispanic persons of other races (38.7%) were more likely to report sleeping less than 7 h than non-Hispanic whites (34.9%). There were no differences in self-reported sleep duration between men and women. Nonworking adults, those with at least some college education, and single people were significantly more likely to report getting less than 7 h of sleep.

Snoring was reported by nearly half (48 %) of respondents, and its prevalence generally increased with aging. Men (57%) were more likely to report snoring than women (40%).

About 38% of adults reported unintentionally falling asleep during the day at least once in the preceding month. This behavior was most likely in those between 18 and 24 years and those over 65 years. There were no differences between men and women in the frequency of this behavior. Those who were unemployed, unable to work, or homemakers/students were significantly more likely to report unintentionally falling asleep during the day, but those with at least some college education were less likely to report unintentionally falling asleep than those with less education. Never married adults (43%) were significantly more likely to report unintentionally falling asleep during the day than married adults (36%). Those who reported getting less than 7 h of sleep a night were more likely to report accidentally falling asleep during the day at least once in the previous month.

Nearly 5% of the respondents reported falling asleep while driving in the month before the survey. People who were 65 years or older (2%) were much less likely to report this behavior than persons aged 25 to 34 years (7%). Hispanics, non-Hispanic blacks, and non-Hispanics of other races all were significantly more likely to report drowsy driving than non-Hispanic whites. Men were more likely (5.8%) to say they had fallen asleep while driving compared with women (3.5%). No significant differences were observed by educational level or marital status. Those who reported getting less than 7 h of sleep a night were more than twice as likely (7.3% vs 3.0%) to report falling asleep while driving in the previous month.

Drowsy driving is a significant public health risk, since it puts not just the driver but also those in the car and on the road with the driver at risk. The prevalence of this behavior is not precisely known, and I am not sure that these two data sets help to clarify this issue. The NSF poll and the CDC survey contain divergent information about the frequency of drowsy driving in America, with 5% of those in the BRFSS survey and 37% of those in the NSF poll acknowledging this behavior. This is a big difference, and I am not sure of the reasons for it. The question on the NSF poll was “Thinking of the past month, how many times have you driven a car or motor vehicle while feeling drowsy?” Response options were: 3 or more times a week; 1 to 2 times a week; 1 to 2 times a month; less than once a month; or not at all in the past month. This is not identical to the BRFSS questions (“During the past 30 days, have you ever nodded off or fallen asleep, even just for a brief moment, while driving {categorized as yes or no}?”), but it’s remarkably similar. The respondents in the NSF poll were younger and less ethnically diverse than those in the BRFSS sample, which could account for some of the difference. The BRFSS estimate is probably more reliable, since it comes from a much larger sample.

While these data don’t tell us precisely how often drowsy driving happens, they do provide insight into the major risk factors. Some are preventable, and some are not. Male gender, non-white race, and youth are the immutable factors associated with drowsy driving in the CDC report, as were being employed and sleeping less than 7 h a night. The NSF poll reinforced the findings that not getting enough sleep and being younger are associated with drowsy driving. The NSF poll confirmed that the Epworth Sleepiness Scale predicts drowsy driving. Indeed, the Epworth Sleepiness Scale is probably the best-documented predictor of sleepiness-related crash risk (Howard et al. Am J Respir Crit Care Med. 2004; 170[9]:1014).

The take home message from these reports is that the first step in the workup of the drowsy driver is to ask how much sleep the patient gets at night. Short sleep duration is a more common cause of impaired driving than is obstructive sleep apnea (Pack et al. Am J Respir Crit Care Med. 2006;174[4]:446). And our youngest, most inexperienced drivers appear to be at greatest risk. There is considerable concern about cell phone use while driving. The NSF report suggests that cell phone use while sleeping may also increase crash risk!