The simple act of moving the clock ahead one hour for daylight saving time is costly for the broadcasts, since the hour that turns from darkness to light happens to be the hour in which they are shown in most of the country.
It's not just a one-week phenomenon. The newscasts will have to deal with smaller audiences until the clocks are pushed back in the fall.
"What it shows is that a large proportion of the people that watch the news are not watching because they watch the news," said news consultant Andrew Tyndall. "They're watching it because they happen to be home when the news is on."
Both NBC's "Nightly News" and ABC's "World News" lost a million viewers from week to week, the Nielsen Co. said. The "CBS Evening News" lost 600,000. That's a total of 2.6 million, or a little more than the entire audience for the NBC sitcom "Community" last week.
While the situation isn't unusual, each newscast lost more viewers in the week-to-week comparison than they did between 2012 and 2011.
"This is part of a predictable cycle every year, so we know to expect a slight dip in viewership when people are enjoying longer hours of daylight," said Patrick Burkey, executive producer of "Nightly News." ''We approach the broadcast with the same mission every day regardless of what time the sun sets."
"Nightly News" had an average of 8.1 million viewers last week (5.4, 11). ABC was second with 7.2 million (4.9, 10) and CBS had 6.4 million viewers (4.3, 9).
In prime time last week, an estimated 10.4 million people watched Sean Lowe propose to Catherine Giudici in the finale of season 17 of "The Bachelor." That's up 13 per cent over the audience that watched last year's finale, with an even bigger increase among the 18-to-49-year-old viewers that ABC considers most important for its advertisers.
Meanwhile, PBS reported that the third season of "Downton Abbey," which concluded last month, represented the most-watched drama on the public broadcaster in all time.
CBS averaged 8.6 million viewers (5.5 rating, 9 share) in prime-time to win the week. Fox had 6 million viewers (3.6, 6), ABC had 5.8 million (3.8, 6), NBC had 3.8 million (2.5, 4), the CW had 1.19 million and ION Television had 1.15 million (both 0.8, 1)
Among the Spanish-language networks, Univision led with a 3.3 million viewer average (1.8, 3), Telemundo had 1.3 million (0.7, 1), UniMas had 480,000 (0.3, 0), Estrella had 190,000 and Azteca 90,000 (both 0.1, 0)
A ratings point represents 1,147,000 households, or 1 per cent of the nation's estimated 114.7 million TV homes. The share is the percentage of in-use televisions tuned to a given show.
For the week of March 11-17, the top 10 shows, their networks and viewerships: "The Big Bang Theory," CBS, 15.9 million; "Person of Interest," CBS, 14.34 million; "American Idol" (Wednesday), Fox, 13.44 million; "NCIS," CBS, 13.18 million; "Two and a Half Men," CBS, 12.18 million; "NCIS: Los Angeles," CBS, 11.95 million; "American Idol" (Thursday), Fox, 11.93 million; "Elementary," CBS, 11.33 million; "The Bible," History, 10.87 million; "The Walking Dead," AMC, 10.84 million.
ABC is owned by The Walt Disney Co. CBS is owned by CBS Corp. CW is a joint venture of Warner Bros. Entertainment and CBS Corp. Fox and My Network TV are units of News Corp. NBC and Telemundo are owned by Comcast Corp. ION Television is owned by ION Media Networks. TeleFutura is a division of Univision. Azteca America is a wholly owned subsidiary of TV Azteca S.A. de C.V.