Excerpt from "40 DEVOTIONS FOR HORSE LOVERS" - available at Amazon. (Free until Midnight Pacific Time 1/9/2012)
He makes me lie down in green pastures, he leads me beside quiet waters. (Psalm 23:2 NIV)
Horses sleep lying down. In movies they often depict horses that lie down as sick or in pain, so most people don’t know that they need to lie down to get REM sleep. If they can’t lie down and get deep sleep, they become sleep deprived and develop disorders. They can have narcoleptic type fits that could cause them to fall over during times when they get a chance to relax, like while being groomed.
In order to lie down and rest, they need to be in a predictable environment with a “guard on watch.” This is why you’ll sometimes see one horse lying down while another stands over him. If they are in an environment that is unpredictable, they will worry about predator attacks or even attacks from other herd members that do not “like” them. If they live alone, they sometimes fear falling into deep sleep because they have no one to warn them if danger threatens.
The attribute that David ascribes to God in this Psalm is His ability to give us a place of peace and rest in our hearts. If we trust God, our hearts can become a predictable place where no worry can permeate. He will stand guard over our hearts, and will protect us from danger so we can rest.