-On the verse
by Yackov it says "He placed a rock under his head".
-The Midrash says this was to protect him from wild animals.
-A rock under the head would not keep away wild animals. Rather it is
referring to Lilim which are referd to as 'wild animals'.
-Yackov never saw Keri in his life and this is one of the tricks he used,
he would always place a rock under his head as he slept.
-The Ari writes that it is a big Tikun to do this. It greatly helps to
prevent Keri and keep away Lilim.
rock under your head and do the following Kavanah before you go to sleep.
One can wrap
the rock in a pillow case if he wants.
-Also if one does not have a rock he should visualize that there is a
rock and he should do the Kavanot.