> I don't use a set of blackout curtains, but I know several friends that say it makes a real difference. Have blackout blinds on every window upstairs so tha

> I don't use a set of blackout curtains, but I know several friends that say it makes a real difference. Have blackout blinds on every window upstairs so thats its dark enough during summer mid day sun to sleep. They keep the heat out during the summer (to the point I dont need the air conditioning on albeit on the hottest days and the warmth in during the winter which contributes to energy saving, the only downside is the air gets stagnant in small buildings. I believe a lot of German homes also have external blinds over their windows for similar reasons plus they offer a layer of security making it harder to break in, but then what do the Germans know? 100lux is quite bright, I have a lux meter and here in the UK 100-200lux is a really cloudy winters day level of brightness, where as a bright summertime day will exceed tens of thousands lux for comparison. Its because light affects the release of melatonin black out blinds are fitted. Melatonin increases the release of stem cells and stem cells play their part in repairing the body, but like I say earlier, CO2 levels building up cause the body to be stimulated even during sleep so sleep is not as refreshing as it could be in small homes and almost all UK homes are small, but hey the CO2 helps contribute to an increase in GDP and thats all that counts!