I have been using CircO2 for about six weeks. I am in my 60's, female. Prior to starting this product I woke for several hours several nights per week, and lack of sleep was severely affecting me in the daytime. Since taking the product I have had only one very poor night. If I wake up, I am able to go back to sleep. I think this is because my whole circulatory system 'relaxes' with the product, which is what I had hoped for. My blood pressure was moderately high. Very pleased! I am putting a four not five star rating because of the cost of this product. I am already trying once not twice per day because of it and would love to find a way to get same effect cheaper!