Robert is having issues with his FitBit reading correctly. He hears that it may be due to his tattoos. Is that true? Leo says it is a known problem with people who have tattoos on their wrists. Tattoos can cause the red light used to read your blood flow and heart rate to be inaccurate. There's a ring, called the Aura, or the Motiv, that can not only do the same but also track your sleep. Not cheap at around $200, but it's an option.