Indeed nothing can replace electricity. Using candles or oil lamps might be Ok for short term, but for the long term it might have side effects for eyes. I think the best way is to use sun light as much as possible and leave less work for evening time when real light need grow up. Effectively planning things and finishing work on day time is good to save energy and have good sleep enhancing one's health strongness. Children should be controlled not to play video or computer games at night and movies should be limited for one movie/ a day.