I picked Old Age as the answer to this. The Question is.... For what is the phrase "full of sleep" a metaphor?... Does anyone agree with me?

"When You Are Old"
By William Butler Yeats
When you are old and grey and full of sleep,
And nodding by the fire, take down this book,
And slowly read, and dream of the soft look
Your eyes had once, and of their shadows deep;

How many loved your moments of glad grace,
And loved your beauty with love false or true,
But one man loved the pilgrim soul in you,
And loved the sorrows of your changing face;
And bending down beside the glowing bar

Question

I picked Old Age as the answer to this. The Question is.... For what is the phrase "full of sleep" a metaphor?... Does anyone agree with me? 

"When You Are Old" 
By William Butler Yeats
When you are old and grey and full of sleep,
And nodding by the fire, take down this book,
And slowly read, and dream of the soft look
Your eyes had once, and of their shadows deep;

How many loved your moments of glad grace,
And loved your beauty with love false or true,
But one man loved the pilgrim soul in you,
And loved the sorrows of your changing face;
And bending down beside the glowing bar

anonymous · Answer

> rest of it<

a little sadly, how Love fled
And paced upon the mountains overhead
And hid his face amid a crowd of stars.

anonymous · Answer

Choices....
A. old Age
B. The End of the day
C. near death

PLEASE!! tell me if i'm wrong or not

bibby · Answer

full of sleep = close to death

anonymous · Answer

thank you so much