"Losing My Mind" is the fifteenth episode of the fourth season of Grey's Anatomy and the 76th produced episode of the series. It is also the 85th produced episode of the Grey's Anatomy franchise. It was broadcast on May 15, 2008.
The hospital buzzes over the arrival of Walter Tapley, a founding father of cardiothorastics and the former mentor of Richard whose unexpected request pushes the Cheif to encourage Erica to perform a risky procedure. Dr. Wyatt refuses to let Meredith quit therapy after a disagreement while Alex learns the truth about Ava's condition. Cristina struggles to escape her dark place and takes her anger out on Lexie and Callie tries to make sense of her newfound feelings for Erica as Mark tries to turn over a new leaf.
- "The problem with being a resident is you feel crazy all the time. You havn't slept in years. You spend every day around people in massive crisis, you lose you're ability to judge what's normal in yourself or anyone else and yet people are constantly asking you how they're doing. How the hell are you supposed to know? You don't even know how you're doing."
- "Don't wonder why people go crazy, wonder why they don't. In the face of all we can lose in a day, in an instant, wonder what the hell it is that makes us hold it together."
- "Walk Like An Egyptian" - The Puppini Sisters
- "Your Red Dress (Wedding Song At Cemetery)" - Alaska In Winter
- "Uh Oh" - Electrocute
- "About Today" - The National
- "The Wolves (Act I & II)" - Bon Iver
- "Sky" - Joshua Radin feat. Ingrid Michaelson
This episodes' title references the song Losing My Mind, originally sung by Maroon 5