Steve Erickson’s review published on Letterboxd:
Subpar for Mike Flanagan. Very upfront about its themes of mortality and grief, but suffers in comparison to THE BABADOOK (which it kept calling to mind, although reviews here mention PAN'S LABYRINTH.) It never quite achieves the nightmarish surrealism, settling for jump scares and badly animated butterflies instead. The lack of violence and relatively positive vibe led to a dilemma for Flanagan: how to make this story scary? Unfortunately, while "atmosphere" might be the right answer, BEFORE I WAKE lacks the subtlety for it.