Tonight with your 13 to 17 year old
The prompt
“How can you tell the difference between being tired and being sad?”
What to listen for
If they can articulate a real distinction, sad feels heavier, tired just wants sleep, that emotional self-awareness is a genuinely valuable skill, and it means they're less likely to mistake one for the other and just push through when they actually need support.
If they say they can't really tell the difference, that's common and worth taking seriously without alarm; it just means this is a skill still being built, and you can help by naming what you notice sometimes, gently, as an offer rather than a diagnosis.
A flat "I don't know" is a fine place to land too, you can leave it as a question they might think about later, not one that needs solving tonight.
What this tells you
This shows you how well they can read their own emotional state, which affects how much they might need you to help name what they're feeling versus figure it out on their own.