1)
Why does it mention Shenos and Tenumos?
1.
Orchos Tzadikim (Sha'ar ha'Atzlus DH Ken): Laziness brings sleep to man's nature.
2.
Malbim: First he sleeps his fixed sleep, and afterwards dozes.
2)
What is the significance of Chibuk Yadayim?
1.
Rashi: One who sleeps, he folds his arms.
2.
Malbim: Even after he awakes from dozing, he folds his arms to lie on his bed and does not do anything.