Let's put it this way, sir, the phosphorus in the products starts to reflect the light as soon as you take it, it retains the energy it gathers in the morning for a certain time of the day, and then it doesn't start to reflect. In other words, as a usage suggestion, if you turn on the light of the room you stuck it in before going to bed at night for half an hour, it allows the stars to shine for 2 hours. The closer and stronger it receives the light, the longer its brightness and duration will be. As we said, you don't need to hold it up to the sun before use, it shines as soon as it collects energy, but you can see it shining in the dark. We wish you a nice day.