Lennon wrote the song at a Transcendental Meditation camp when he could not sleep; the Beatles had gone on a retreat to study with the Maharishi Mahesh Yogi in Rishikesh, India. After three weeks of constant meditation and lectures, Lennon missed his soon-to-be wife, Yoko Ono, and was plagued by insomnia, which inspired the song. One of dozens of songs the Beatles wrote in India, "I'm So Tired" detailed Lennon's fragile state of mind. It was also an open letter to Ono, whose postcards to Lennon in India were a lifeline. "I got so excited about her letters," he said. "I started thinking of her as a woman, and not just an intellectual woman." Lennon later said of it: "One of my favourite tracks. I just like the sound of it, and I sing it well". The song is in the key of A major and features Lennon singing the main tune in a slow, flowing fashion while the rest of the band sings the chorus, which is repeated twice and yelled at the end of the second time. The theme of insomnia complements Lennon's earlier song "I'm Only Sleeping" on the Revolver album.
At the very end of the song, what seems to be nonsensical mumbling can be heard in the background. The mumbling, if played backwards can be imagined as something along the lines of "Paul is a dead man. Miss him. Miss him. Miss him." This only adds to the many supposed references to the "Paul is dead" conspiracy scattered throughout the White album. Mark Lewisohn has said that the nonsensical mumbling is actually Lennon muttering, "Monsieur, monsieur, how about another one?" Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.