I am a licensed beauty professional as well. ACV is not what made Mary's hair fall out, it was most certainly the peroxide. But I will say, unless it is a conditioner, I don't recommend leaving any product on overnight. Everyones skin is different, including your scalp, and will react different. Also, vinegars are cleaning agents, as are baking sodas...mixing these products together is essentially stripping the hair of anything. Salons use baking soda to strip the hair. ACV is a great product, but should not be applied to the hair in full strength (more is not better in this case). In fact, (I did not see it so I cannot be sure) but I would be willing to bet that Mary's hair did not fall out, but actually broke off. Am I saying not to use it, absolutely not, I love ACV, I use it all the time...use it in moderation...equal parts with water, do not leave it in overnight.