1)
What is the Chidush of lying down without fear?
1.
R. Yonah: [Even] when you lie on the road, "u'Shchavtem v'Ein Macharid" (Vayikra 26:6). You will be secure not only when awake, rather, even when you lie down; the Torah will guard you.
2.
Malbim: This is Bitachon.
2)
Why does it say "v'Arvah Shenasecha"?
1.
Rashi: Your sleep will be pleasant when you do not have sudden fear.
2.
R. Yonah: Dreams and visions will not confound you - unlike "v'Chitatani va'Chalomos" (Iyov 7:14).
3.
Malbim: You will not have bad dreams or other harm that comes while sleeping.
