The Twilight Zone (1959)

S5E12 Ninety Years Without Slumbering

An elderly man is consumed by the belief that his life is tied to the functioning of his grandfather clock. He becomes increasingly anxious, convinced that if the clock were to cease ticking, it would signal the end of his own days. This fear drives him to obsessively maintain the clock, checking on it constantly to ensure it continues to keep time, as he grapples with the unsettling notion of mortality and its connection to the passage of time.