We recommend starting with just 10 minutes and then working your way up to a longer amount of time. Slow and steady as they say. (See the product manual for instructions on doing a pre-test to gauge your sensitivity to light).
Everyone reacts to light differently, so it’s important to find the amount of time and distance that works best for you. Some people use a light therapy lamp for as little as 15 minutes a day while others will use the same lamp for 2+ hours. When you start to feel like you’ve had too much coffee or a little amped up from the light, you’ll know you’ve hit your own personal max.