The length of time that CBN gummies or any other form of CBN will stay in your system can vary depending on a variety of factors, such as the dosage, the person's age, weight, and individual metabolism, and the specific condition being treated. In general, CBN is thought to have a shorter duration of effects than THC and is not typically detectable on drug tests, as they are not designed to detect non-psychoactive cannabinoids like CBN.