If you believe latest research you can forget everything you’ve heard about how drug use is the result of a complex mix of social and biological drives. News.com.au report that researchers at the University of California and Harvard University have discovered a link between a lack of sleep and the likelihood of illegal drug use. It’s said it can spread through a teen network “like a contagion”, infecting siblings, friends and acquaintances as many as four degrees’ separation removed.

The researchers mapped the sleep patterns and drug use of more than 8000 teenagers. They found that a teenager with one friend who sleeps fewer than seven hours is 11 per cent more likely to sleep fewer than seven hours. Teenagers with a friend who uses marijuana – the most popular drug among US adolescents – are more than twice as likely to use pot themselves. The researchers also said teenagers with a friend who sleeps less than seven hours per night are 19 per cent more likely to use marijuana. The study said the spread of poor sleep habits from one teenager to another was partly to blame for an increased likelihood of drug use.