I don't know what level you're talking about but honestly, I have two 100 watt bulbs in the ceiling of my bedroom which is about 10' x 10'. So it's pretty bright. From the point where I'm in bed and I flip the switch at the foot of my bed to turn off the ceiling lamps to the point where I can clearly see the dark figures and walk around my room by the light of my VCR display is around 5 minutes. Beyond 5 minutes, I can't "sense" myself seeing any more clearly. I've sat in bed for more than half an hour and not been able to notice any more sensitivity than I had after the first 5 minutes or so.