Place it as the opening reply in a wake-up scene, before any explanation or follow-up line. Follow it with a yawn or alarm sound if you have one, or cut straight to the other person's confused reaction for contrast.
About this sound
A very short French spoken clip of Crystale Montgommery answering groggily with 'Oui? Excusez-moi, je dormais.' The sleepy, slightly embarrassed delivery turns a simple wake-up apology into an awkwardly funny moment that feels instantly relatable. It comes from the television series Le coeur a ses raisons.