15th day question?

I was very very tired on my 15th day...i only worked about 2 hours....I could hardly wake up ...the whole cleanse has been a breeze for me except that day...i heard you get 5x's the red blood cells by your 14th day..i wonder if thats why...does everyone report being tired on the 15th day? I am on day 16 now so i feel a bit less tired than yesterday