Just a quick note before my long post... I make everything sound simple below, but it actually can be quite a challenge. So I feel like I need to say that the important thing in the dark night is to experience what you can and learn from those experiences as best you can, but if you need guidance, psychological therapies, or other meditation tools -- then FIND THEM AND USE THEM. There is no benefit to needlessly suffering.
Many of the same experiences that occur during mental illness occur during meditation practice. The difference is someone provoking them through meditation has more room to retreat -- they can use less effort in practice, they can practice less, they can stop practice and take a break. Mental illness doesn't have that room to retreat, the person's entire life is dominated by negative thoughts/emotions.
Both psychological therapies and meditation work by experiencing those states and integrating them. A good psychologist will help you re-experience traumatic situations/feelings, in small doses so that they can be understood and experience without being overwhelmed. Meditation does the same thing but more quickly because the person has a sane/stable platform to work from. If you don't have that platform, meditation will only overwhelm you. Never be in a rush to push further at the expense of having a good foundation.
If psychological treatment helps with the "Misery" nana, great! If meditation helps with depression, great! But base your practice on the reality of what is occuring. If you are truly feeling overwhelmed, get support for what you are going through.
And ideally, find that support _before_ getting deeply into meditation practice. It is a lot easier to search for a teacher, a therapist, a mediation group when you are not depressed or freaking out. People underestimate how helpful it is to have a senior student or teacher to check in with periodically. It makes life easer and practice better.
So, that said...
Rainbow, you might like the interview that is found on this page:
http://www.wisdompubs.org/book/manual-insight
The progress of insight is what happens when we take the things that we identify with and notice them as objects in awareness. It follows a predictable pattern, but there are limits to the extent that it applies to a given person's practice.
The important thing to understand about the progress of insight is that it reflect patterns seen in meditators on retreat doing a particular practice. The further you get from that context, the less applicable it is... but it is amazing how it appears to have some pretty good applicability to lay people doing consistent high-quality home and off-cushion practice.
Aside: Looking back on my own life, I think the first few stages has even broader applicability. I've noticed that all through my 20s and 30s, I would go on long, solo trips in remote area and there was a pattern of becoming very aware of my thoughts and body, then a period of finding everything frustrating, then everything was rich and spiritual, usually a night of vivid or surreal dreams, then laziness, then a heavy depression. Very similar to the first several days of being on retreat and almost perfectly lined up with the progress of insight stages.
Basically, it's the old unpeeling the onion metaphor. There are layers and layers of identification, but a finite number.
If someone steps out of the trance of normal discursive thinking about their life, the first thing they notice is that they have thoughts and sensations in their body. Mind and body.
If someone investigates mind and body, they will see that they influence each other. Cause and effect.
If someone investigates cause and effect, they will see that we are most of what we do is actually driven by a visceral reaction to the unsatisfactory aspects of experience. Three characteristics.
If someone investigates the visceral reactions to the three characteristics, they see how these reactions are like dominoes hitting one then the other then the other. Arising and passing.
When they can simply watch all that happen, the body might have a small taste of the space between the dominoes. Arising and passing event.
At this point, meditation is a comedy of errors, which comes from trying to "not see" what is actually happening. It's a more detailed map because this is where people really need help.
Instinctually and somewhat unconciously, the person will try to "find" the spiritual experiences of the A&P of the nothingness of the A&P event. They don't find it and instead it feels like everything good is slipping away. If they actually just watch that happen, then they get the insight into the nature of Dissolution -- things don't stick around.
Instinctually and somewhat unconciously, the person will have a sense of loss of control and be surprized by something and evokes primal terror. If they don't see fear as an experience in awareness, then the meditator gets lost in thinking about all the things that evoke fear. If they actually just watch that happen, then they get the insight into the nature of Fear -- surprise is surprise, no big deal, and even fear is fear, no big deal.
Instinctually and somewhat unconsciously, the person will want to protect themselves from surprises and will instinctually create an ongoing, low-level sense of misery to fill up the space. It's a coping mechanism. But it the person sees misery as misery, then they get the insight into the nature of Misery.
Likewise with Disgust. Long term misery feels awful. Disgust is an empowering coping mechanism that allow someone to feel more in control and more powerful. "I am disgusted!" But if the person sees disgust as disgust, then they get the insight into the nature of Disgust.
Likewise with Desire for Deliverance. The person is somewhat empowered and thinks, "there must be a way out of this". There is a focus on problem solving, perfecting practice, finding better teachers, etc. It has the flavor of some confidence and passonate seeking. But if the person see this as another reactive pattern, then they get the insight into the nature of Desire for Deliverance.
Likewise with Reobservation. The person is now reobserving everything they went through, all the strategies, all the attempts to find the experience they think will make them happy. It has the flavor of desperation and failure. If they see this desparate feeling of "nothing works" as just another reactive pattern, then they get the insight into the nature of Reobservation.
Low Equanimity is finally realizing that fighting experience or trying to find a difference experience other that what is actually happening is impossible.
High Equanimity is being mostly at peace with this and continuing to sit, mildly curious about "if all of these experience occur within awareness, then what is awareness? what is mind? what is knowing?"
Stream Entry happens when the pervasive non-reactivity of equanimity (not grabbing at objects, not searching for objects) allows for momentary non-grabbing. The meditator doesn't "do" anything. It's more like when a sun runs out of fuel and it collapses into itself.
Hope this helps in some way.
This stuff isn't "figured out" by thinking, it's by becoming intimate with what is actually occuring. Either people go through these stages or not.
But all meditation has the basic insight which becomes more refined and nuanced over time: the realization "oh, this event which I thought was me is actually just a "mind object" in my awareness."
