For those of you who have only written and studied the literal meanings of
sleep and death, here is some further information.
Sleep and Death were two lesser Roman gods. They dwelt in the underworld. Dreams were sent to ascend into the hearts of all men. They were passed through two different gates, on had horns which true dreams were passed, and the other was made of ivory for false dreams.
There is a common saying which states "I do not sleep for it is the cousin to death" but it is even closer to that, they were brothers.
Dreams were sent out by Somnus, the god of dreams, and were accompanied by Sleep and Death. The area of sleep is near Cimmerians, in a deep, dark valley of no sunrise, and only shadows. And there is only silence and the sweet lulling of the stream Lethe which is the river of forgetfulness.
Morpheus was the son of Somnus, and he originally held special dust in a sachel to spread over people to allow them to sleep. Originally, sleep was like dieing slowly. To sleep each time gave you a little taste of death each time you fell into a slumber, but he then was ordered to make sleep a peaceful and calm state of being. His new job was to take the form of anything or anyone and to bring dreams to those in need of them.