The state you are trying to achieve in TMI is one in which your attention is bright and clear in an absolute sense, and simultaneously your general awareness is as clear and wide as possible.

Peripheral awareness is often the first thing to degrade if you are experiencing dullness. The initial sensation is often of the peripheral awareness muting – objects and sounds and sensations becoming less vivid. As dullness progresses, objects merge and become less distinct – a kind of murkiness.. Finally, as dullness gets strong, the scope of awareness narrows, from being very wide to narrowing on just the field of attention.

The last part of the progression is often random imagery showing up… often the kind of imagery you get just before falling asleep.

You should train yourself to notice these conditions. At the first sign of dullness, you should take steps.

The book talks about varying kinds of remedies for dullness, but those remedies were all far too weak to treat the kind of dullness I encountered. I suspect my body thought meditation looked similar enough to falling asleep that it assumed that was what I was trying to do.

The first kinds of interventions I needed were physical. I needed to break the meditation, get up, sometimes exercise a little to get the heart rate up. Anything to convince my body it was not time for sleep.

The second kinds of interventions I needed were mental. I would break the meditation and try to get mentally exited about what was going on. Generating curiosity about what would happen next helped.

The kind of dullness I had felt like plummeting down a steep slope. I explicitly started training my brain to recognize the characteristics of dullness, and then intervene. This began changing the dullness progression to a slower process that was easier to catch. The techniques in the book were often then enough, and eventually dullness stopped being a problem. Training myself out of dullness was an epic process probably requiring half as much effort as, but in addition to, the TMI techniques themselves.