kicker wrote:
Could you provide the context it was used in? As that would help narrow down it's meaning.
All depends on the context. In almost all scenarios I can think of it implies a low keyed/depressed (not the diagnosis) response to something that many would perceive as abnormal for the situation (not reacting when the situation calls for a reaction such as crying/laughing/getting angry). Unless it is being used in a sarcastic context where the person it is being applied to was overreacting (IE jumping up and down or becoming irate over junk mail).
It is most often used by clinicians to describe the person's affect.
I had a neuropsychologist tell me tests showed a low emotional energy. I wasn't in a state to ask follow up questions at the time and I thought I could just look it up myself later. I'm not having much luck.