I think of mania and depression as kind of like being on a boat. The waves come and go but are always vary in strength. The waves die down but it doesn't just stop overnight, it happens gradually. Not the vest analogy. But I think at least for me when depressed or manic not all days are as severe as other days. When I am manic getting back to normal is a slow process, some days I will feel normal but some symptoms linger around longer, same as depression for me. When I have severe mania it can take me a few months to be completely symptom free.