Why do colors seem to affect our mood?

Answer: Mostly through links we learn from experience and culture

Each color triggers its own specific brain chemical — No color triggers its own dedicated brain chemical. The eye turns light into nerve signals, and any mood shift depends on what the color means to you in that moment.

Colors change our body temperature, which shifts mood — Color doesn't meaningfully change body temperature; a red room is no warmer than a blue one. People sometimes feel that a red room is warmer, but that's an association, not a physical change.

Mostly through links we learn from experience and culture ✓ — Most color-mood effects come from associations: red goes with stop signs and warnings, green with plants. Because they're learned, they vary by culture, with white meaning purity in some places and mourning in others, and lab studies usually find the effects are small.