|“|| Lydia: "Yeah, I know what parasomnia is, Mom. But what about the feathers?"|
Natalie: "People with night terrors have done far stranger things than eating their own pillows. And anyway, I already told her to take the rest of the day off, but she said she didn't want to miss her first day."
Lydia: "Let me try. I don't have any more classes. I'll take her home and talk to her."
Natalie: "Lydia, she's having trouble sleeping. If she needs help beyond that, we'll find her professional help."
Lydia: "I couldn't agree more."
Deaton informs Scott that the talons he broke off of the hands of Belasko, the mutant Werewolf Scott and Kira fought, were actually the talons of a harpy eagle, and warns him that someone may be trying to change the rules of the supernatural world. Stiles investigates Theo , as he's convinced that Theo is up to no good. Liam reveals his true nature as a Werewolf to his best friend Mason, and tells him about the supernatural world. Lydia and Parrish try to help a girl named Tracy, who has been suffering from hallucinations and night terrors. Tracy later wanders into the lair of the Dread Doctors, who inject her with a serum that seemingly turns her into a Werewolf as well.
- Tyler Posey as Scott McCall
- Dylan O'Brien as Stiles Stilinski
- Holland Roden as Lydia Martin
- Shelley Hennig as Malia Tate
- Arden Cho as Kira Yukimura
- Dylan Sprayberry as Liam Dunbar
- Linden Ashby as Sheriff Stilinski
- Seth Gilliam as Dr. Alan Deaton
- Ryan Kelley as Deputy Jordan Parrish
- Cody Christian as Theo Raeken
- Khylin Rhambo as Mason Hewitt
- Susan Walters as Natalie Martin
- Kelsey Chow as Tracy Stewart
- Victoria Moroles as Hayden Romero
- Tom T. Choi as Ken Yukimura
- Michelle Clunie as Mrs. Finch
- Salvator Xuereb as Mr. Stewart
- Marti Matulis as The Surgeon
- Douglas Tait as The Pathologist
- Caitlin Dechelle as The Geneticist
- John Duff as Twins' Alpha
- Elise Robertson as Mrs. Raeken
- Nadia Buer as Stephanie
- Kevin Symons as Mr. Raeken
- Claire Bryétt Andrew as Sydney (uncredited)
- The title refers to "parasomnias," which does not just mean night terrors-- in reality, it is a medical term for an entire category of sleep disorders, some of which have already been referenced in the series. This category breaks down further into non-rapid eye movement (NREM) parasomnias and REM parasomnias.
- The former category includes confusional arousals (awakening in a confused state), sleepwalking (also known as somnambulism), sleep/night terrors (like that experienced by Tracy Stewart in this episode), teeth grinding, restless legs syndrome, sleep sex, and sleep-related eating disorders.
- The latter category includes REM sleep behavior disorder (during which the person acts out their dreams due to a lack of muscle atonia), recurrent isolated sleep paralysis (like Stiles Stilinski experienced while possessed by the Nogitsune), and catathrenia (breath-holding and expiratory groaning during sleep).
- Beacon Hills High School
- Guidance Office
- Mr. Yukimura's Classroom
- Mrs. Finch's Classroom
- Parking Lot
- Stewart House
- Tracy's Bedroom
- Beacon Hills Animal Clinic
- Exam Room
- Beacon County Sheriff's Department
- Sheriff's Office
- Beacon Hills Preserve
- Bridge over the creek
- Yukimura House
- Kira's Bedroom
- Stilinski House
- Stiles' Bedroom
- Raeken House
- Dining Room
- "Last Days of Dancing" by Maja Francis
- Scott arrives at school for his first day of senior year and last first day ever. Kira joins him, and he puts his arm around her as they head to class.
- "Take It To Reality" by Alison Wonderland
- Scott, Lydia, Kira, and Sydney sit down at their lab tables in AP Biology
- "War of Hearts" by Ruelle
- Theo tells Scott and Stiles the story of how he was supposedly bitten by an Alpha
- "Wild Ones" by Bahari
- Stiles angrily punches his Jeep, and Scott takes his pain until it no longer hurts at all
- "Hold Me Down" by Mansionair
- Scott and Kira talk and make out in Kira's bedroom