Because you have been sleeping for a while without drinking anything, your pee is typically more concentrated in the morning. The pee will be slightly darker. It will provide a stronger results line; typically, the urine is ideal for an accurate test. If it is not tested right away, first-morning pee can be stored for up to three days at 36°F (2°C) or for eight hours at room temperature 59-86°F (15-30°C).