Many philosophical works have referred to death as sleep. Now I wonder... may be the day and night is a scaled down model of life and death. Physically one is awake in the day and asleep at night. And spiritually, you are manifested in life and dormant in death. Death is just a resting phase for the weary soul.. until it can wake up again.
Its almost as if the clue to decode the mystery of life is right here where we can see it.
Then again, day is when the body works and retires at night. The soul sleeps in the day (for most of us) and wakes up at night. We can catch a glimpse of this soul in that semi-conscious state of half asleep and half awake.