I have a Philip Stein Teslar and I have absolutely noticed a difference in my sleep patterns at night and concentration during the day. I even bought another one for my husband... but he didn't notice any difference. We figured it out that the new Philip Stein watches are made with a different chip... so we returned it and bought a men's watch that actually was Teslar and he too started noticing a difference! I recommend the Teslar watches to anyone! If Oprah supports it they must be doing something right!