This song also marks one of the first ever usages of
backwards guitar. Technically, it is the second
Beatles song to use this technique, since
Tomorrow Never Knows was recorded first. However, I'm Only Sleeping comes earlier on
the album, so it's easier to call this the
first one.
The guitar parts took six hours to record; first George Harrison had to write the solos, then figure out how to play them backwards, then finally put them to tape and reverse the recording. He actually plays two electric guitars, one clean and one distorted, further lengthening the time required.
The song was probably written almost entirely by John Lennon. In that period, John and Paul were still mostly writing together but starting to branch off. McCartney probably added a chord here and there, or helped with the bridge, but little more.
Also of note is that John would later return to this idea two years later, with The White Album's I'm So Tired.