In general, on a clear day, meaning no cloud cover or minimal cloud cover, you want to get this sunlight exposure to your eyes for about 5 minutes ... On a day where there's cloud cover, so the sun is just peeking through the clouds or it's dense cloud cover, you want to get about 10 minutes of sunlight exposure to your eyes early in the day. And on days that are really densely overcast, or maybe even rainy, you're going to want to get as much as 20 or 30 minutes of sunlight exposure.