This is a word that several people, professionals and others, who know or have observed my wife have used in relation to her general mood. I have to agree that is usually sums her up. And I'm very grateful for it and pleased for her.
But of course such a state has come at a price. When she was tormented and frustrated by hallucinations and by her inability to cope with some of the basic tasks of everyday living, there were still many times when she was able to articulate what she was feeling - whether bad or good - and relate meaningfully to other people, including me. It's not that these abilities have disappeared entirely - it's still possible to understand what she is feeling from her body language, behaviour, the occasional few words and even by getting the gist of her mixed up 'conversations' where made up words now predominate though there are sometimes perfectly sensible phrases and even sentences (even if you ignore the words, the patterns of the conversations, the intonation and the emphases, can also be revealing).
She has a new granddaughter about a month old. I think she understands this, and she smiles a lot when we are talking about the baby and when she is holding her. But then she smiles a lot anyway.
It saddens me enormously that her grandchildren will never really know the person who raised their mothers, and whom I fell in love with.