When Congress voted to move the start of daylight savings time up three weeks last year from April to March, the idea was to save energy. But a side effect has been to put a damper on TV ratings.

The extra hour or so of daylight has the effect of drawing people outside and away from their televisions. The impact was always apparent come April, but now, with daylight savings taking effect so early, the effect on television is much more notable, especially during the first hour of primetime.

On Sunday night, overall household TV usage at 7 p.m. slipped 7 percent week to week, from 60.4 percent to 56.1 percent, according to Nielsen. Among adults 18-49, the dip was even sharper, down 12 percent week to week, from 35.5 percent to 31.1 percent.

On Monday, ratings in that demographic were low across the board on broadcast at 8 p.m. ABC’s “The Bachelor” special had the franchise’s worst-ever rating for an original episode, NBC’s “My Dad is Better Than Your Dad” slipped to a series low, and Fox’s new “Canterbury’s Law” had the lowest premiere this year for a Monday night drama.

Last year, according to a Fox analysis of Nielsen data, the start of daylight savings time resulted in a decline of 6 percent for TV viewing levels among adults 18-49 compared with the same time the previous year, while slipping 9 percent compared to the previous two months.

As the weeks went on, the year-to-year declines diminished, but by that point the networks were already nearing May sweeps.

Certainly other factors affect viewership levels. The writers’ strike, the increased usage of digital video recorders and a generally lackluster crop of midseason programs are also reasons for year-to-year declines.

But these may also serve to worsen the daylight savings crunch. If viewers don’t feel a strong need to catch new shows or are satisfied relying on DVRs to tape their programs, they’ll feel even less pull toward the television when daylight hours stretch later and allow for more time outside, especially when the weather warms up over the coming weeks.

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Meanwhile, in broadcast ratings for the week ended March 9:
 
Among adults 18-49, Fox was first with a 4.5 rating and a 12 share, followed by NBC at 2.4/6, ABC at 2.3/6, CBS at 2.2/6, Univision at 1.6/4, CW at 0.9/2, MyNetworkTV at 0.5/1, Telemundo at 0.4/1, TeleFutura at 0.3/1, and Ion and Azteca at 0.1/0.
 
Among adults 18-34, Fox led with a 3.9 rating and a 12 share, followed by ABC and Univision at 1.8/6, NBC at 1.7/5, CBS at 1.4/4, CW at 1.1/3, Telemundo at 0.5/1, MyNetworkTV at 0.4/1, Telefutura at 0.3/1, and Ion and Azteca at 0.1/0.
 
Among adults 25-54, Fox was first with a 5.1 rating and a 12 share, followed by NBC and CBS at 2.9/7, ABC at 2.8/7, Univision at 1.5/4, CW at 0.9/2, MyNetworkTV at 0.5/1, Telemundo at 0.4/1, TeleFutura at 0.3/1, Ion at 0.2/0 and Azteca at 0.1/0.
 
Top five English-language Big Five shows (18-49s): 1. Fox’s “American Idol - Tuesday” 10.6; 2. Fox’s “American Idol - Wednesday” 10.4; 3. Fox’s “American Idol - Thursday” 9.4; 4. Fox’s “Moment of Truth” 6.1; 5. ABC’s “Lost” 5.4.
 
Top five English-language Big Five shows (total viewers): 1. Fox’s “American Idol - Tuesday” 28.44 million; 2. Fox’s “American Idol - Wednesday” 28.32 million; 3. Fox’s “American Idol - Thursday” 26.5 million; 4. Fox’s “Moment of Truth” 14.72 million; 5. ABC’s “20/20: The Royal Family” 14.14 million.
 
Top five Live+7 English-language Big Five shows (Households, week ended Feb. 24): 1. ABC’s “Academy Awards” 18.8; 2. Fox’s “American Idol - Tuesday” 16.9; 3. Fox’s “American Idol - Wednesday” 16.8; 4. Fox’s “American Idol - Thursday” 14.0; 5. ABC’s “Oscars Red Carpet” 13.4.
 
Top five Live+7 English-language Big Five shows (18-49s, week ended Feb. 24): 1. Fox’s “American Idol - Wednesday” 11.9; 2. Fox’s “American Idol - Tuesday” 11.8; 3. ABC’s “Academy Awards” 10.8; 4. Fox’s “American Idol - Thursday” 9.0; 5. ABC’s “Lost” 6.7.
 
Show on the rise: “The Biggest Loser,” NBC, Tuesday 8 p.m. Even against “American Idol,” NBC’s weight-loss reality program jumped 21 percent week-to-week among 18-49s from a 2.9 rating to a 3.5.
 
Show on the decline: “Oprah’s Big Give,” ABC, Sunday 9 p.m. Although it still pulled a respectable 4.0 rating among viewers 18-49, “Big Give” was off almost 25 percent from a 5.3 rating for the previous week’s series premiere.