Gen 15

When the sun was setting, a deep sleep overcame Abram, and a horror (a terror, a shuddering fear) of great darkness assailed and oppressed him.

I've often felt this in my sleep.  (not that my life is anything important. But it gives me comfort.) I think everyone has at one time or another. This dread that seems to come after important battles and contact with the divine. We embrace the notion that we are a part of a picture much larger than we often confess it to be. There are children in whose destiny we shape. There are nations turned. There will be rebellions, slavery, injustice and battle still to come but the end is blessing .

13And [God] said to Abram, Know positively that your descendants will be strangers dwelling as temporary residents in a land that is not theirs [Egypt], and they will be slaves there and will be afflicted and oppressed for 400 years. [Fulfilled in Exod. 12:40.]