In terms of the amount of insight a human being has, there may be peaks and valleys. When someone lacks insight, they will probably be ignorant of that fact. When insight returns or to begin with appears, its owner could marvel at past foolishness and may be frustrated about it.
The level of insight is a general characteristic which isn’t always specific to one's psychiatric condition, or even to having a psychiatric condition. If someone lacks insight about their condition, it is likely that they will also lack insight in other areas.
(People, with or without a psychiatric illness who drink a lot of alcohol will tend to lack insight: and this is due to alcohol being a depressant.)
Whether or not medication has been added to the equation, a mentally ill person's insight is an issue. Insight varies according to who and when. Ideally, insight about the illness (or about anything in life) becomes developed through learning from someone else's mistakes. More likely, a person learns from their own mistakes because pain is involved.
Mental illness as well as the medications used to treat it may affect mental capacity. While medication does change the mind, it does not necessarily produce an unaware person. Untreated mental illness is far worse.
It helps if someone can accurately evaluate their own consciousness. This awareness might only come after a long period of being stabilized. Learning from mistakes is another category of insight which involves reflecting on memories of the recent or distant past.
In my past, I had an unfortunate ability to ignore facts that were directly in front of me.
Mental illness can interfere with learning. The more stabilized someone is, the more intact their learning mechanisms will be. When I reached the ten year point that followed my most recent and hopefully last episode of psychosis, my mind really began to wake up.
I am fortunate in the fact that I am usually playing with a full deck. However, if I am off medication for any significant period, my brain will give me a severe relapse of psychosis. Maybe one of the reasons why I am treatment compliant is due to the monumental amount of suffering I have experienced in my psychotic episodes.
Going off medication suddenly after being heavily medicated for years will have an effect that resembles being wiped away by a tsunami.
In successive episodes, the recovery time after each one increases. Like with many diseases, if not treated aggressively enough, schizophrenia can create a great deal of organ damage. However, in the case of mental illness, the organ we are dealing with is the brain. From a few weeks of going without medication, the ensuing recovery time can be measured in years.
Taking medication doesn't flip a switch and make you normal. It helps treat the worst of one's symptoms but it doesn't by any means fix the whole problem. I have not always been aware of this.
It is not always possible to distinguish between behavior from the illness or from the person who has the illness. A psychiatric condition sometimes comprises a component of character that is not easily separable from the rest of the person.