The phrase "a flat mood" is correct and usable in written English.
It can be used to describe a state of emotional dullness or lack of enthusiasm.
Example: "After hearing the disappointing news, she was left with a flat mood for the rest of the day."
Alternatives: "an apathetic mood" or "a dull mood".
Don't allow yourself to make faces, to frown or grimace at people--or even go into a flat mood, as if you are so tired.
Sudden change in mental functions, such a flat mood, impaired judgment, memory loss, or a lack of interest in daily activities.
There was a rather flat mood among journalists leaving the Galen Centre after Microsoft's keynote briefing at this year's E3 trade show.
Andrew Harding is BBC African correspondent: andrew harding (@BBCAndrewH) Strange, flat mood now.
But it was the inspiration for Kuhn and his team to reason that "if the flat mood of schizophrenia could be lifted by the drug, then could not a depressed mood be elevated also?" Under the brand name Tofranil, imipramine went on to become the first antidepressant — and one of the first blockbuster psychiatric drugs.
But these excerpts from my notes at the time (edited somewhat for clarity and concision) convey the flat mood: "Mo Yan's talk — the first half is dreary and wooden and the Chinese journalists around me whisper that he didn't write it, it was written by the writers' association.
It would have been encouraging to see UK PMI jump above the psychologically important 50 barrier this month, but at 48.4 purely indicates a flat rather than declining mood.
The physician who examined Cho noted that he had a flat affect and depressed mood, even though Cho "denied suicidal thoughts and did not acknowledge symptoms of a thought disorder".
He described his mood as 'angry', with a flat affect.
