It’s been more than half a century since Helen Reddy sang, “I am woman, hear me roar!” but the line remains as good a mantra as any for Amy Adams ’ ferocious lead performance in Marielle Heller ’s tamer-than-expected “Nightbitch.” Identified only as “Mother” in the credits, Adams plays a woman who gave up her career to raise her son, but is only now, four years in to stay-at-home motherhood, realizing just how much the experience has changed her. “Transformed” might actually be a better word, since her primeval awakening gives off serious werewolf-movie vibes.

This mother believes she might be turning into a dog. Novelist Rachel Yoder opens “Nightbitch” with the words “for my mom & for all the moms.” To some, that might sound like a warning — “male readers (and childless cat ladies) not welcome here” — when in fact, the dedication doubles as a sort of prescription.

Instead of expecting women to reinvent the proverbial wheel, “Nightbitch” ought to be required viewing “for all the moms.” Like Yoder’s book, Heller’s bitingly literal adaptation operates on the premise that motherhood is something primal and instinctive, a universal experience that binds humans to other wild animals. But it’s also a strangely well-kept secret which obliges women to navigate its challenges alone.

While a thousand mommy bloggers and maternity book authors have dedicated their lives to demystifying the experience, “Nightbitch” speaks to all thos.