“[...] You know who works mostly night shift? Mothers. Because they like to be free for their kids [and] to be home during the day. So, it’s a lot less wild and woolly, and a lot more boring and sedate than you would think.” - Noah Wyle via this interview
Who is on our night shift that we know of?
Abbot, Shen, Ellis, Toomarian, Henderson, Walsh, Lena, Mateo. As far as I know, none of these characters have ever been mentioned to have children. Abbot is a widower, Lena has ex-husbands, but other than that, I don't believe family relations have been mentioned for the rest of them.
Furthering that though, this is, plain and simple, a very sexist thing to say. He doesn't say parents, he specifically uses mothers, and implies that because it's mothers, there is not as much interesting material. Which, what the fuck?
On our day shift in season two, four of our cast members are parents. Three are mothers. Langdon's a father, and Al-Hashimi, Dana, and McKay are all mothers. None of them are boring. None of them are sedate. All three of those female characters are strong-willed, drive conflict within the story, and actively move the plot forward.
The idea that night shift being mostly mothers and therefore being lame because of that is just gross. It leaves such a bad taste in my mouth. He is proven wrong with his own television show, which just highlights how distasteful of a thing this was to say.
For a show that prides itself on a diverse cast with strong women characters, this is an awful quote to have a creative lead casually giving.