You Sleep More Than You Claim You Do

A couple years ago I wrote about how people don’t work nearly as many hours as they claim they do. That is, there’s a big gap between how many hours people estimate they “usually” work versus how many hours they log when asked to keep a time diary, especially for people who already keep long hours. (The typical person who reported having worked 40 hours, for example, actually worked about 37; people who claimed a usual week of 75 hours worked 50.) This discrepancy could be due to fuzzy memories, or a desire to sound more industrious, or both.

The same problems may plague self-reports of shut-eye.

A recent Gallup report, based on a survey question about how much time people “usually” sleep, says the average American gets 6.8 hours of slumber a night.

Most recent numbers are based on telephone interviews conducted Dec. 5-8, 2013, with a random sample of 1,031 adults, aged 18 and older, living in all 50 American states and the District of Columbia. The margin of sampling error is plus or minus 4 percentage points.

The Labor Department’s 2012 American Time Use Survey, on the other hand, reports an average of 8.7 hours. The latter is based on a sort of day-after time diary; respondents are interviewed about how they spent their time on the previous day, for each hour of the day. Here are the numbers broken down by age and sex.

Source: American Time Use Survey, Bureau of Labor Statistics. Data include all persons 15 and older and include all days of the week. These are annual averages for 2012.

Maybe there’s some difference in how people interpret the Gallup versus American Time Use Survey question. For example, Americans might tell the Labor Department that they spent the hours of 11 p.m. to 7:30 a.m. asleep, when a decent chunk of that time was actually spent tossing and turning and obsessively checking the alarm clock. And maybe when Gallup asks about “usual” hours of sleep, respondents instead count only the successfully unconscious portion.

The surveyed populations are also slightly different (18 and older for Gallup, versus 15 and older for the Labor Department), and teenagers do sleep more than the rest of population â€" but the inclusion of a few more teenagers seems unlikely to increase the overall average by nearly two full hours. Even the age range with the fewest hours of sleep on average (people around 45 to 54 years old) still report substantially more sleep than the overall Gallup numbers suggest.

Maybe, as with estimated versus documented working hours, people just systematically exaggerate their industriousness when asked abstractly about their daily habits. I suspect that has to do with the workaholic American culture, but people in Belgium, Russia, China and Japan have also been found to overstate their work hours, based on similar metrics. I don’t know whether there’s evidence that people from these or other countries also might understate their slumber time; if you know, feel free to mention it in the comments.