Analysis of My Bed is a Boat

My bed is like a little boat;
Nurse helps me in when I embark;
She girds me in my sailor's coat
And starts me in the dark.

At night I go on board and say
Good-night to all my friends on shore;
I shut my eyes and sail away
And see and hear no more.

And sometimes things to bed I take,
As prudent sailors have to do;
Perhaps a slice of wedding-cake,
Perhaps a toy or two.

All night across the dark we steer;
But when the day returns at last,
Safe in my room beside the pier,
I find my vessel fast.