Well, I don't know how much I can offer, as I am very new to the cushion. What I can tell you is from the perspective of an "accidental yogi."
I've only been practicing for a week. That week has been supplemented by my introspective nature. Within my first two days of practice, I went through the full cycle of DN phenomena, on and off the cushion. I was free of the "symptoms for 2 full days, and then fell back into them. This has pretty well convinced me that I accidentally crossed A&P at a previous time in my life, without any practice. During that time I have been looking back on life, trying to assess the origin and impact this has had on my life. I believe I have isolated the A&P event to an experience I had when I was 18 (I'll be 30 next month). The culprit appear to be a week long series of Dextromethorphan "trips" that were characterized by a deeply spiritual tone. The week culminated with an experience where I felt like I had connected to the universe in a fundamental way. As this was a chemically induced meditative state, it was very off balance. This connection, combined with a drug addled experience led me to believe I had become a divine incarnation. I don't really want to talk about the rest, but suffice it to say, I did not touch DXM for a year after that. The next time I used it was one of the most terrifying experiences in my life. I spent 6 hours being afraid I was dying. I never touched the stuff again. My answers are based on my reexamination of the last decade, and the last week of meditation.
Willoughby Britton:
I also asked Ron Crouch, and he said that there were 2 simultaneous cycles: one long meta-cycle that represents the yogis "cutting edge" i.e. the furthest stage reached; and then mini cycles within that.
Although two "formally" observed cycles is hardly a sufficient data pool, I can say that this concept certainly resonates with my experience. In the two cycles I've observed, I ave had the background theme of desire for delivery. The rest of the cycle seems like a "spike" of the specific DN characteristics, in order. The length of the cycle seems to depend on how much time I spend on the cushion, as an inverse correlation.
Willoughby Britton:
So I welcome any thoughts on this topic, with particular interest in the following:
Do the stages of insight/DN continue off the cushion ( and without the need for further meditation)?
I have to say yes. No only do they progress without further time on the cushion, but in my experience, it will progress without any formal practice at all.
Willoughby Britton:
How could we reconcile the Dan Ingram vs U Vansa experiences?
This is pure speculation, but maybe the people with more severe expressions of DN lost hope and never returned. That would leave U Vansa with students with very mild off-cushion "symptoms" that they never actually connected to DN.
In Dan Ingram's case, his open discussion on the subject would be likely to draw in chronic DN yogis.
Willoughby Britton:
What factors determine how long the cycles are?
In my case, I think the symptoms may have been drawn out or shortened based on how long after the A&P event they took place. In retrospect, I think my first cycle may have lasted as long as 4-7 years. To be fair, I that could have been prolonged by the philosophy I adopted. I had a fundamental feeling that no reality actually existed, but since the illusion of reality was all we had to work with, we had to embrace the illusion. That willful defiance of A&P understanding could intensify and prolong the DN experience if, as it has been suggested, DN is the result of the perceptions of conditioned reality hanging on for dear life after having experienced them as illusion. From that point, the cycles appear to get shorter. In the last two years I can see full cycles that run around 3-4 months each. In some instances, stress may have accelerated the rate.
2 months ago, I had a dramatic, devastating change in my life. This change threw my entire idea of the future out the window.
Since the, I have been experiencing cycles rapidly. The cycles vary in length anywhere from a few days, to a few hours.
Contributing factors as I see them: stress, time passed since A&P, and determination to grip conditioned views.
Willoughby Britton:
As a sleep researcher, I am prone to think these cycles (which U Vans described as "automatic and somewhat mechanical, once set into motion) resemble other biological rhythms (like menstrual cycles, or circadian rhythms, which have inter-individual differences, as well as external influences). But if they are so basic, then why aren't they mentioned in the suttas?
I may be wrong here, but weren't the people involved in the transcription of the suttas all monks? They would probably not have gone more than a night's sleep without regular practice. Combine that with the fact that they see life as dukkha anyway. The lay practitioners they dealt with may very well have experienced off-cushion DN symptoms, which the monks mistakenly recognized as the dukkha of unenlightened existence.