One-Eyed Night Vision

I heard once that if you get up at night and need to turn on a light, you should keep one eye closed in order to keep your night vision. The open eye will adjust to the light and the closed eye will still be able to see in the dark once the light is turned off.

I've tried this a few times and it does seem to work. I suppose it's an interesting phenomenon because eyes usually do everything in sync with each other. For me, the sensation of having each eye adjusted to a different level of light was a bit unpleasant.