Don’t get too close to a tired ;you could start losing sleep as well.When one ager starts sleeping less, her friends and others in her social (67) soon lose sleep, too, according to new research. Our social networks can (68) our behaviors and moods. Political scientist James Fowler of the University of California has studied these effects and previously found that obesity, smoking, and (69) happiness can spread through networks of people (70) based on their relationships. Fowler (71) his study of a network of more than 8000 7th-to 12th-grade students and their sleeping and smoking (72) . He and colleagues (73) a web of connections between each student and his or her friends. In one of these friend webs, a gang of sleepless boys (74) the middle of the mess, where the most (75) kids landed--the so-called "cool" kids. The researchers found that the (76) central a landed on the map, the greater chance that he or she got less than 7 hours of sleep per night. Drug use was also contagious(具传染性的), the team (77) . Each smoking friend increased the (78 that a student used marijuana () (79) 42%. Both sleepless and drug-use contagions could still be felt four-degrees of separation (80) , influencing a friend of a friend of a friend’s friend. Most surprisingly, the researchers found a link between (81) of sleep and drug use. (82) a ’s friend slept less than 7 hours, her chances of using drugs went (83) by 19%. And that means that (84) sleeplessness spreads throughout a friend (85) , drug use spreads as (86) .