I've been what my doctors call mixed for a few weeks. I have classic euphoric mania mixed with random thoughts of depressive and negative thoughts and a disphoric, agitated depression but euphoric mania comes back and they cycle back and forth. They called this mixed but I'd bet mixed can be different for everyone. I was considered mixed when I had agitated disphoric mania too. They just do there best to describe the mood phase and if it has elements of mania and depression simultaneously, it's called mix. But criteria might change from practitioner to practitioner.