Hello Ananda,
I second what you said ..
Though I'm a beginner in AYP and have integrated
the basic techniques quite recently to my regular
"diet", it is obvious to me that working on the energy
level accelerates the purifying process far more quickly
and deeply than diet - for exmaple - approach..
Breathing techniques along with meditation have a detoxifying
effect and relaxing effect on both the immune and nervous system.
No surprise that we gain in health and are able to get rid off
any virus or toxin very quickly..
One thing though: we are in winter, it is colder and more humid out there..
And the early morning is particularily humid and cold.
So it is expected that you get sick in the morning.
In terms of energy, you are simply "throwing out" the excess of
yin (or water/cold) energy from your system, to keep the balance with the outer system..
Also waking up before dawn has, in itself, great benefits..
Even without practices.. the atmosphere is highly conductive in terms of prana and Heaven energy..
this is the best time for pranayam and meditation!
I wish I could manage to wake up earlier.. it happens sometimes,
and I feel grateful when it happens! coz the silence of early morning is unique.
Love..