Last month, the US magazine Advertising Age put the evolving impact of the Internet in dramatic terms when it said that Yahoo and Google's total ad revenues this year could rival the combined prime-time ad revenues of ABC, CBS, and NBC -- a stunning achievement for the companies and a watershed moment for the Internet as an advertising medium.

A US Government Study of a Day in the Life of America - summary from Advertising Age:

The average American sleeps 8.6 hours. Workers spend a third of the day on the job. The No. 3 activity, after sleep and work, is watching TV.

Consumers spend half their leisure time -- and effectively 11% of their lives -- in front of the tube. That’s strong evidence of the commanding role TV plays in the lives of consumers even as the ad industry debates the future of the 30-second spot and the issue of slipping broadcast ratings.

Time Use Survey
The facts come from the American Time Use Survey, the government’s first comprehensive time study. The survey, offering detailed data on how different demographic groups spend their days, puts hard numbers behind common assumptions. Women spend four times as much time on housework (an hour a day) as men do. Employed men on average put in an hour more at work (eight hours) than employed women (seven hours).

Adults in households without children have more leisure time (5.6 hours) than homes with children (4.2 hours). One not-so-shocking finding: Working mothers with young children have the least leisure time of any adults (a bit more than three hours).

“A lot of the data weren’t surprising,” said Diane Herz, a division chief at the Bureau of Labor Statistics, the survey’s sponsor. Dig deeper, though, and the findings become more intriguing.

Reading paper-based publications
Reading, for example, relates directly to age: The older you are, the more time you allocate to reading for personal interest (books, magazines, newspapers). Teens spend just seven minutes a day on reading (not including homework or time on the Internet); people age 20 to 34 read for 10 minutes. The 45-to-54 demo reads for nearly twice as long (19 minutes). The biggest demo for reading? Age 75-plus -- a contingent with more leisure time (nearly eight hours) than any other age group and plenty of time to read (72 minutes).

The survey was based on interviews in 2003 with about 21,000 people age 15 and older. The Bureau of Labor Statistics published initial findings last fall and continues to analyze and release more detailed data. It will issue annual updates starting later this year to show how use of time changes over time.

Internet data lacking
The survey has limitations. Ms. Herz said the government hasn’t found a good way to track multitasking -- cooking while watching TV, for example -- and so it asks consumers to identify their primary activity. The survey also lacks deep Internet data.

Ms. Herz said the Bureau of Labor Statistics designed the ongoing survey so new questions could be added. She said it will consider questions from private enterprise if companies or industry groups can find at least one government agency to sponsor and submit proposals.

A look at some areas where Americans spend their time:

LEISURE
The old and young have the most leisure time. People age 35 to 44 have the least free time -- and, not coincidentally, spend the most time taking care of children.

Leisure time depends on such factors as age, work, education and children in the household, but Ms. Herz noted that consumers across demo groups tend to spend roughly half their free time watching TV.

Still, actual hours in front of the tube vary considerably. College-educated workers spend 1.4 hours a day -- 6% of their 24 hours -- watching TV. Consumers with a high-school diploma but no job spend four hours a day -- 17% of their existence -- watching the small screen.

Americans tend to do less physical activity -- exercise and sports -- as they get older. Teens are active 40 minutes a day; people from age 35 on spend 15 minutes or less being active. Consumers with bachelor’s degrees or higher tend to do more.

SHOPPING
First, the bad news for marketers: On an average day, only four in 10 Americans buy something. Now the better news: Americans on average spend 24 minutes a day shopping; 20 minutes on a weekday; 27 minutes on Sunday; and 42 minutes on Saturday. (The results raise the question as to why many retailers are fixated on Sunday newspapers, arriving after the big shopping day.)

Women on an average day spend 50% more time shopping than do men. This partly reflects that women are more frequent shoppers. On days when men do shop, the time they spend isn’t that different from women.

Shopping time has a decided education skew. College-educated consumers spend more time shopping than high-school graduates, who spend more time than those without a diploma. This skew probably reflects that college graduates typically have more disposable income.

WORK
The study proved out the work-at-home trend: Nearly one in five people does some or all of their work at home.

The more education consumers have, the more likely they are to work at home. Just 9% of workers without high-school diplomas and 13% of those with diplomas reported working from home; nearly a third of college graduates did their jobs from home.

SLEEP
Sleep is Americans’ favorite use of time. Americans spend an average of 8.6 hours a day sleeping -- 8.3 on weekdays, 9.0 on Saturday and 9.6 on Sunday. Women generally sleep a few minutes longer than men -- except for teens, where the boys out sleep the girls.

Teens age 15 to 19 rule the roost on sleep at an average 9.4 hours a day, beating the runners-up -- the 75-plus crowd -- by more than 20 minutes a day.