Part of the sluggard run.
Quick answer
Motion without travel. He is moving all night and he is exactly where he started.
Read both lines
The image is one of the most economical in the book. A door on its hinge swings, works, makes noise, and never leaves the frame, which is a perfect description of a certain kind of effortful going-nowhere. The comedy is affectionate rather than cruel, and any reader who has spent a morning turning over knows the joke is fair.
Placed second in the run it also builds an argument: verse 13 gave his reasoning, this gives his motion, verse 15 will give his appetite, and verse 16 gives his self-assessment. Four verses, four angles, one man who has not moved. The saying also declines to call him tired, which it easily could have. It says only that he turns, which leaves open the possibility that he is comfortable, and comfort is a harder thing to argue a person out of than exhaustion.
Related: Proverbs 6:9–11 · Proverbs 26:15 · Proverbs 19:15
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.