What makes life sustainable is sleep.

 What makes life sustainable is, quite simply, sleep. Sleep suspends consciousness for hours, temporarily pausing existence to allow rest and renewal. If one goes to bed feeling bad, that feeling often fades by morning—not necessarily because of resolution, but because of the belief in waking to a new, fresh day. Sleep creates a gap between days, a rupture in continuity, which allows each day to feel distinct from the last. But for a person who has lost their sleep, there is no such gap. Days bleed into each other without separation. Life becomes a single, unbroken stream—unceasing, unrested, unrelenting. Time moves forward without pause, and existence becomes a weight that never lifts.