Crossword clues for the word: SEROTONIN The word SEROTONIN has appeared as an answer to at least 8 crossword clues on different crossword puzzles. Crossword clues for SEROTONIN Showing 1 to 8 of 8 results Clue(s) Certain neurotransmitter It could improve your mood to snore in turns Mood regulator translated into Norse Natural mood alterer Neurotransmitter associated with sleep Neurotransmitter linked to depression So-called happy neurotransmitter What makes everyone happy?