There are many benefits from sleep - it is a biological necessity, many problems can be caused by lack of sleep or poor quality of sleep - but for a Christian it is necessary to understand the spiritual or 'existential' role of sleep because each Man's life is built-around sleep.
When Shakespeare wrote the above quotation - from The Tempest - he meant that our whole life was a little thing and then we died; but often a whole life feels like a big thing, an incomprehensibly and unmanageably big thing.
So, our whole life is divided into little lives of days - and each day is separated by sleep; which is a kind of little death, in the sense of bringing a pause to conscious endeavor, striving, doing, planning.
Thus each day we are active, then inactive; extraverted then intraverted; each day we start and we finish.
(It might have been otherwise; but this is how it is.)
Each morning there is expectation, hope or dread; then there is doing and struggling and happiness and sadness, pleasures and pains; and at the end of the day, as sleep approaches, there is of necessity a coming to terms with that day, and a surrender of will, and an enforced helplessness as we are plunged into unconscious passivity - a requirement for trust that sleep is not the end but a transition between days.
So, an average human life is both long and short - it is a single archway, and it is cyclical and recurrent - sleep makes our lives into a sequence of reincarnations as the soul feels that it leaves the body then re-enters the body.
This is not a matter of dreams remembered. Sleep does its work whether we dream or not, whether we remember our dreams or not.
Awakeness is experienced as a explicit state, by contrast sleep is implicit; we know what sleep does from indirect evidence, from the difference it has made.
What this difference from having slept actually is, is seldom known by direct introspection but is a matter for inference, for guessing, for trial and test perhaps.
We plunge into sleep, we emerge from sleep changed; we find ourselves awake and starting a new day - we feel different from the way we were yesternight. Something has happened, some things have happened - whatever they are is now a matter of experience.
(Sleep is experience.)
And this is life - it is serial and it is cyclical; each diurnal cycle does not return us to the beginning but to a somewhat different point; each day is a unit and a 'fresh start', but not a discrete unit since we carry our-selves over from the day before.
And yet that self to which we return on wakening has been changed somewhat.
And this is life.