Zach and Tori Roloff are preparing their daughter for a big day.

In an exclusive clip shared with PEOPLE ahead of this week’s episode of

Little People, Big World, the couple explains that their daughter Lilah, 4, has

to go to a doctor’s office to make sure she’s sleeping okay.

“Tonight is Lilah’s sleep study. I’m going to be the one taking her to her sleep study,” Zach begins in a confessional. “Yeah, nervous about it. It’s going to be a long night, I think. And I don’t see Lilah…it going well.”

The scene then cuts to the toddler running around the house wearing her backpack and pajamas.

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“She’s very excited, babe,” Tori says. “Little night away with Dad. She thinks she’s going to a spa or something.”

In a confessional, Tori explains why Lilah has to go to a sleep study.

“People with Dwarfism, I think a sleep study is just recommended to make sure that there’s not obstructed sleep apnea,” the mom of three shares.

“I think it’s also to make sure that she is safe when put under anesthesia,” Zach adds. “Our airways are built slightly different than other people and there is maybe a higher threat of, you know, maybe something going wrong.”

Back at their house, Zach tells his daughter, who looks very excited, that they won’t be coming back until the morning.

“I keep telling her they’re going to put stickers all over her head and we’re going to have a nurse there and things like that. So I hope she has a good idea, but who knows with her,” Zach says in the confessional.

“I don’t think she has a good idea,” Tori adds.

“She gets it in her head and then she gets scared and then she has a hard time recovering,” the proud dad says.

In addition to their daughter, the couple is parents to sons Josiah, 21 months, and Jackson, 6.

During a previous episode this season, Tori recalled a recent incident from one of Lilah’s dance classes.

“Lilah has started taking dance classes and she’s doing just ballet right now. I was just thinking she really needs to be socialized and if I put her on a sports field she’d probably think that we were killing her,” said Tori.

“In front of all the dance moms, one little girl came out and said she had to go to the bathroom so then Lilah comes out and says she had to go to the bathroom,” she continued.

“And I’m like no, no, no we’re not going to play this game. Just because someone else is going pee-pee we’re not going to do it. Well five minutes later she peed her pants right there and I felt like a terrible mom, so bad. It was like a whole big thing too.”

Little People, Big World airs Tuesdays at 9 p.m. ET on TLC.