UVB Light Treatment at Hospital

Hi, So today was my 2nd session of my light treatment at the hospital for my P. I have guttate which is more or less over my whole body bar my face, scalp and chest, it's a mixture of pea sized spots, coin sized spots and pretty large patches on the front and back of my thighs and forearms. I noticed after my first treatment on Monday all patches went completely red and were very itchy that night even with moisturizer on. My 2nd session today my patches seem to all be a lighter red and don't seem as itchy this time, again I moisturized up when I got home. I may be getting carried away here and potentially seeing what I want to see but is it possible I'm seeing a slight change after only 2 x 13 second sessions? I'm assuming these UVB chambers you go in and ridiculously powerful. I've been told I'll be 15 seconds on Monday, then 18 and so on but by week 4 I'll be on 1 min and so on. Thanks