Lyric discussion by ht70 

Cover art for While You Were Sleeping lyrics by Elvis Perkins in Dearland

Think Elvis is looking back wishing his mother overslept and missed that fateful flight. Just a beautiful song.

While she was sleeping:

"you (she) rolled your eyes as the world burned" "the heavens fell, the earth quaked" "the time changed" and so forth

He also says "full of dreams, you overslept"...wishing she overslept and missed the flight.