Arising and passing of phenomena pertaining to the mind and matter process (Samudaya-vaya-dhammanupassi)
through sensations (as you experience phenomena and any characteristic of the aggregates or characteristics of matter though a sense door - vidita vedana - and also make you whole body sensitive - Sabbakayapatisamvedi)
any mind and matter phenomena creates sensations
internal and external sources (Ajjhatta-bahiddha)
absence of clinging and craving of any type
So it is good to be aware of the reading so you don't miss any facts, but this might not liberate you from stress and misery.
If awareness alone did the trick then the happiest people would be the circus performers, gymnasts, etc.
So what ever you are absorbed in, be aware of the sensations and their arising and passing, keeping your mind firmly equanimous and devoid of craving and clinging. This is the type of awareness you have to develop in daily life including when reading.
Reading on its own creates verbal fabrications but if you can limit thought proliferation this is good. The though proliferation can be limited by:
calming the fabrication - less distraction from bodily pains
though observing the speed and length off the breath cycles - may be not easy while reading
passively looking at sensation, ideally in a small area like the upper lip
anchoring the mind
realise your mind has left the anchoring object
objectively looking at sensations or experience created by the distracting object