Since CBS’s “Survivor” went on its traditional midseason hiatus in mid-December, NBC’s 8 p.m. sitcoms have been reaping the benefits of a less-competitive timeslot.

“My Name is Earl” and “The Office” grew for the second straight week, both hitting season highs, as they also won the timeslot for the second straight week.

“Earl” averaged a 4.7 adults 18-49 Nielsen overnight rating, its best since last spring, at 8 p.m. “The Office” built to an impressive 5.0 at 8:30 p.m., a season high and its best since one year ago.

“Earl” was up 9 percent over last week’s 4.3, while “Office” jumped 16 percent over the previous week’s 4.3. Season to date, the shows are up nearly 50 percent over the network’s average in the same timeslot a year ago.

Among total viewers, “Office” had its best outing in a year, with 10.2 million, while “Earl” had its best showing since March, with 10.9 million.

NBC seems to be benefiting from the absence of “Survivor.” Last night CBS averaged a 2.7 among 18-49s in the timeslot, or half of what “Survivor” usually does. NBC does not, however, seem to be stealing viewers from ABC timeslot competitor “Ugly Betty,” which was up week to week in 18-49s.

It may well be that “Survivor” viewers who usually record the NBC sitcoms are watching them live, as both shows are popular among viewers with digital video recorder.

This is a promising development for NBC as “Survivor” gets ready to return in a few weeks. With that show weakening significantly in its most recent season, it’s possible these new viewers won’t migrate back to CBS.

Meanwhile, with its first new “Grey’s Anatomy” in weeks, ABC took first for the night among viewers 18-49 with a 5.7 average rating and a 15 share last night. NBC finished second at 4.4/11, CBS third at 3.0/8, Univision fourth at 1.8/5, Fox fifth at 1.8/4 and CW sixth at 1.7/4.
 
NBC started the night in the lead with a 4.8 average during the 8 p.m. hour for “My Name is Earl” (4.7) and “The Office” (5.0). ABC was second with a 4.4 for “Ugly Betty,” with CBS third with a 2.7 for “Armed and Famous” and Univision fourth with a 2.3 for “La Fea Mas Bella.” CW came in fifth with a 2.0 for “Smallville” and Fox sixth with a 1.9 average for “‘Til Death” (1.8) and “The War at Home” (1.9).
 
At 9 p.m. ABC took the lead in a big way with a 9.3 rating for “Grey’s Anatomy,” about even to its most recent original episode. CBS and NBC tied for second that hour, CBS for a “CSI” repeat and NBC for “Scrubs” (4.0, tying a season high) and “30 Rock” (2.9). Univision and Fox tied for fourth at 1.7, Univision for “Mundo de Fieras” and Fox for “The O.C.,” while CW was sixth with a 1.4 for “Supernatural.”
 
NBC took the lead back at 10 p.m. with a 5.0 for “ER,” followed by a 3.6 for ABC for “Men in Trees.” CBS was third with a 2.8 for “Shark” and Univision fourth with a 1.3 for “Aqui y Ahora.”
 
Among households, ABC led the night comfortably with a 10.2 average rating and a 16 share. CBS was second at 6.5/10, NBC third at 6.1/10, Fox fourth at 2.7/4, CW fifth at 2.4/4 and Univision sixth at 2.3/4.