TORONTO, ONT – The day after the premiere of their film “Nightbitch,” Amy Adams and Marielle Heller are sitting in a Toronto restaurant reflecting on all that went into, as Heller puts it, “birthing” a movie that captures some of the truest, rawest but seldom Instagrammed things about early motherhood.

Their film, which writer-director Heller has described as a comedy for women and a horror film for men, stars Adams as a woman credited only as “Mother.” With her husband (Scoot McNairy) often away on work (and when he’s there, he refers to solo parenting as “babysitting”), Adams’ character experiences a wide range of emotions raising a newborn. She is exhausted and resentful. Fresh postpartum horrors await a glance in the mirror. Animalistic urges bubble up. New powers emerge. The movie turns increasingly surreal. There are dogs.

“I just met her where I was at,” says Adams, whose own daughter is now a teenager. “That was me at that time in my life. It wasn’t a transformation that I made for the movie. I just was like: This is who she is. This is who I am, let’s marry the two and let’s be proud.”

The adaptation of Rachel Yoder’s bestseller that Searchlight Pictures will release Dec. 6, is about as close to the bone as it gets for Adams and Heller. In “Nightbitch,” the rage and bitterness of an over-burdened, self-sacrificing mother — Adams’ character has given up her successful career as an artist — find well-deserved expression. Aside from pulling from Yoder’s book, the movie comes directly from Heller and Adams’ experiences. Extreme as it can be, “Nightbitch” is essentially reportage from a little-documented chapter of parenthood.

Heller, the filmmaker of “A Beautiful Day in the Neighborhood,” “Can You Ever Forgive Me?” and “The Diary of a Teenage Girl,” wrote the script while raising her second child with her husband Jorma Taccone. They had moved out of New York during the pandemic, but Taccone was away for several months working on a TV show.