I also went rallying in my miss-spent youth, early Volvo 122s with 6v lighting. There were comments to the effect that our quick selective times were down to NOT being able to see!
I'd like to add to this topic: In daylight, If you wear those reactolite type of specs, make sure you have a spare pair handy to pop on when entering the tunnel portal. Don't ask me how I know this but I had a bit of paintwork to touch up afterwards!
Ref post 22; I encountered a boat with a VERY bright headlight, coming the opposite direction in Netherton tunnel and on the wrong side of the cut. Very worrying until I discovered that it was a bike on the towpath!!