Much has been written about the importance of a good night’s sleep. The optimal length of sleep time varies from one individual to another, but most studies recommend seven to eight hours of sleep a night for adults. The quality and continuity of sleep are no less important and have an enormous effect on daily functioning and quality of life. The 2010 Social Survey of the Central Bureau of Statistics questioned individuals aged 20 and over about the number of hours they sleep per night and the continuity of their sleep.The data reveals that almost half of all Jerusalemites sleep less than seven hours per night. A total of 5 percent of Jerusalemites reported that they sleep four or fewer hours per night; 42% reported that they sleep five to six hours per night; 48% reported sleeping seven to eight hours per night; and 5% sleep more than nine hours per night. These statistics are similar to the figures for average hours of sleep among residents of Israel.And what about the quality of sleep? Survey participants were asked whether and how frequently they had trouble falling asleep or sleeping through the night. The percentage of Jerusalemites who had trouble falling asleep or sleeping through the night on a nightly or nearly nightly basis was 12%. A total of 9% had such difficulties two or three times a week; 13% had difficulties once a week or less often; and 66% had no trouble falling asleep or sleeping through the night. www.jiis.orgJerusalemites slept better than residents of Haifa, for example, where more than one-fifth (22%) had trouble falling asleep or sleeping through the night, and slightly more than half (54%) never had such difficulties.Survey participants who reported having trouble sleeping were asked about the extent to which their sleep problems affected their daily functioning. Of the Jerusalemites with sleep problems, 40% reported that their daily functioning was affected to a large extent or to a very large extent. In comparison, this figure stands at 29% for Haifa residents, 35% for Tel Aviv residents and 36% for Israel’s residents as a whole.