This is one of the most vicious, cutting songs ever written. Here is a video for it, so you can hear it for yourself, and see the things to which the song refers.

It was, of course, written targeting one specific person, but it isn’t difficult to listen to it, and think of other people to whom this question could — and perhaps should — be asked. In other words, there is no reason, in today’s world, to limit this song to merely being an “attack song” against Paul McCartney, although that was certainly John Lennon’s intent when he wrote it.

When anyone does horrible things — far worse than anything McCartney ever did — this song’s title makes a good question one could ask them: how do you sleep?

After thinking about it, I have come up with five possible answers.

1. Some people lack a conscience, and so are untroubled by guilt — ever — no matter what they do.
2. Delusional people can do horribly evil things, but be convinced that they are moral, righteous, and doing what they should be doing. If you have never encountered such behavior, consider yourself fortunate.
3. Sometimes, people are simply ignorant of how harmful their actions have been. One cannot feel guilty over harm one does not know one caused.
4. Even those who are tormented by their own consciences, and past actions, can still sleep with the aid of sedatives, whether over-the-counter, or prescribed. This is risky, of course, and should only be done under the care, and following the instructions, of a physician. (Yes, I am aware that illegal drugs — or legal ones that aren’t considered medicines, such as alcohol — can also be used for this purpose, but that’s even more risky, and I wish to make it perfectly clear that I strongly advise against doing that.)
5. Narcolepsy.

If you can think of any others, please leave them in a comment.