Blue light can delay melatonin production and make you fall asleep later.

Im interested in finding out how light would effect me if I wake up during the night and get exposed to a short burst of light (1-5 minutes) when I would go the toilet, let the dog go the toilet or I go get a glass of water. Is 1-5 minutes of light exposure enough to make me resistant to falling back to sleep or would my body already have produced enough melatonin as I was previously asleep?