I shoot both eyes open with a 3/16" peep, and have never had a problem with low light. I can see well enough to get a shot, while there's still actually shooting light. I agree with FL also, anything beyond that, it's either too dark, or past time anyhow.

Now when I used to shoot with one eye closed, yes...shooting light rapidly disappears, even with a big peep, long before you could actually still take a shot.