In low spirits

Lydia: I’m coming from Mary’s house.

Sheila: How is she?

Lydia: She is low in spirits.

Sheila: Why? What happened?

Lydia: She didn’t get through her exam.

Sheila: Oh, I’m sorry to hear that. Explanation: Low in spirits/In low spirits - feeling sad

Example: I’ve been in low spirits (feeling sad) lately.