Sleep is proving to be rather illusive these days. Most of it can be blamed on my foot and how it's still mad at me for putting it through another surgery. Someday I'll sleep the whole night through again. I remain ever hopeful.
The Beatles had gone on a retreat in Rishikesh, India to study Transcendental Meditation with the Maharishi Mahesh Yogi. After three weeks of near-constant meditation and lectures, John Lennon couldn't sleep for missing soon-to-be wife Yoko Ono. He wrote this song with her in mind.
I'm So Tired by The Beatles from the 1968 double album "The Beatles" (also known as The White Album)
The Beatles website