Jennifer Lopez got candid with ET about maintaining her priorities -- and looks -- while starring in her first TV series, Shades of Blue.

For the 46-year-old singer and actress, beauty rest is a necessity.

"There is a limit," J.Lo stressed to ET. "You will fall down at a certain point, and mommies can't do that. Mommies have to be good for the babies at all times. They need to know that you're solid and strong and good. Sleep is very important. I get my seven to eight hours sleep no matter what."

WATCH: Jennifer Lopez Is a Beautiful (and Badass!) Cop in First 'Shades of Blue' Trailer

Finding time for adequate rest has become trickier for Lopez while she films Shades of Blue.

J.Lo stars in the NBC drama, which she produces, as single mother Detective Harlee Santos, who gets involved with a "tight-knit group of dirty cops." The stakes are raised when she is forced to work with the FBI's anti-corruption task force and rat out the corrupt cops on her own team.

When her days on set are over, Lopez switches gears from "serious actor mode" to mommy mode, as she heads home to spend quality time with her 7-year-old twins Emme and Maximilian.

MORE: Casper Smart Is Playing a Bad Guy on J. Lo's Series 'Shades of Blue'

"I have to see them because if I don't see them and they don't see me, then it's not happiness," Lopez said. "Like, this morning I had to work out, then I sit down and I have lunch with them before I come over here and then I go, 'You know what? Since we're shooting all the way through, I'll have the kids come over at 6:30. They can bring me dinner because we had some leftovers.' Every day is like that!"

Between her long work hours and the time she carves out for her kids, Lopez admitted she's had less time to be in the gym, but she'll be in tiptop shape for her Las Vegas residency at Planet Hollywood's AXIS Theater, which kicks off Jan. 20.

MORE: Jennifer Lopez Lands Las Vegas Residency!

"I feel a tiny bit out of shape right now, but that's OK, because I 'm about to get in shape," Lopez said. "We'll tighten it back up real quick."

Shades of Blue premieres Jan. 7 on NBC.