Buddhism offers an interesting model of mental acuity. It suggests that a key challenge to progressing in Meditation is “dullness,” (“laya” in Sanskrit) characterized by weak attention, “like trying to see through a dense fog.” It becomes an obstacle during longer meditation sessions because the mind is used to a certain amount of stimulation to occupy its attention, and that’s not supplied during meditation.
This is a familiar problem when doing difficult intellectual work, too: Dullness and distraction in creative work may arise from the same causes as in meditation.
See Moments of consciousness model, after Culadasa for a model which attempts to explain this phenomenon.
Q. Name a few cures for dullness in meditation.
A. e.g. Deep breaths, exhaled through pursed lips; tense all muscles until trembling, then relax; meditate standing; meditate walking; cold water
Q. Why do common cures (“tense all muscles”) work against dullness in meditation?
A. They provide increased stimulus for the mind, decreasing the proportion of non-perceiving moments.