The film's use of a time loop serves as a metaphor for the experience of trauma. Tree's repeated reliving of the same day is akin to the way traumatic events can feel like they are stuck in a loop, replaying in one's mind over and over again. The film illustrates how trauma can disrupt one's sense of time and continuity, making it difficult to move forward. Tree's attempts to change the course of events each day can be seen as a manifestation of her desire to undo the trauma of her past and create a new narrative for herself.
You can find the on various major digital platforms. Availability varies by region: happy death day full movie