bbc, if you don't mind my asking, are your house lights quite bright? What wattage bulbs, for example, do you use in your sitting room? Some of my friends' houses are lit up to an inordinate extent, and I know that would send my brain into wakefulness during the evening. Also, do you go to bed fairly early? If I have to stay up late (for a village event going on until 11pm, say) I don't drop off to sleep quite so easily. Normally we turn in at 10-30pm. I believe it isn't just backlit devices, but any light shining into ones eyes during the evening. Instead of sunglasses in the house, try reducing the wattage of your lightbulbs right down to silly amounts. As I said above, ours are 25 watt (just 2 side lamps!) and we like it like that.