...Then Israel bowed himself upon the head of his bed.
Genesis 47:31c

...And the king [David] bowed himself on the bed.
1 Kings 1:47d

This bowing on the bed is more than just sinking back down in exhaustion. I believe it is also symbolically recognizing the passing of authority and responsibility to the next generation.

Interestingly, without vowel points that were added to the text thousands of years later, the Hebrew word for "bed" (mitah) is spelled exactly like the word for "tribe" (matah). If read as tribe instead of bed, the statement at the end of Genesis 47:31 would say "Israel bowed himself before the head of the tribe."