Researchers in America have analysed data from 765,000 Americans surveyed between 2002 to 2011 by the Centres for Disease Control and Prevention. Combining responses on sleeping patterns with weather station records, they calculated that every 1 degree Celsius increase in nighttime temperatures produced an additional three nights of restless sleep per 100 people per month. Scaled across the entire population of America, this translates to over 100 million extra nights of insufficient sleep each year. To read more go to Nighttime temperature and human sleep loss in a changing climate.