Thanks for the update.
The sensitivity to light is a new report. We will have to keep tabs on this development.
The improvement in morning headaches has been reported by many people using I.T. Your afternoon headach may relate to sitting posture, again raising the seat higher so it is at least level with knees or higher should help this.
Also make sure you drink a little more water, dehydration could influence your dizzy / vertigo feeling. I.T. does remove more fluids initially, even though your need to void is reduced at night, evaporation is more efficient on I.T. due to improvements in body temperature.
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