My brother-in-law asked the original topic question and the combined 50 years of experience in the family was unable to give a positive reply.
What we have figured out is this.
1. Night adaption.
2. Subconscious learning. These were the last lights on and they mark the exits.
3. Improved view out for interested passengers.
4. The warm, dark environment is relaxing, thus having a soothing effect on nervous pax.
5. It says so in th e book!
Anymore guesses?