Dr. James Gangwisch, admits that depression could be causing the poor sleep patterns. However, it was observed that some of these teenagers only developed symptoms of depression after developing poor sleep habits. Lack of adequate sleep has been linked to aberrant mood changes including loss of concentration, impulsivity and anxiety

"Adequate quality sleep could therefore be a preventative measure against depression and a treatment for depression," he added.

Chief executive at the mental health charity, YoungMinds, Sarah Brennan, said "Enough sleep, good food and regular exercise and all essential to stay emotionally healthy. Nearly 80,000 children and young people suffer with depression, yet we are still failing to provide our young people with the help and support to cope with it and prevent it.”

She adds, “Providing parents with information about how to look after your body, for example by getting enough sleep and how to get help if they are worried about their teenager, will ensure problems are tackled early and prevent serious mental health conditions such as depression."

Final point: While it may sound reasonable to assume that adequate sleep may prevent depression this is clearly not so. There are many individuals who do sleep well and yet feel depressed -- clearly indicating that there are many other factors which play a role in development of depression. If sleep was the only factor then sedatives (and not anti-depressants) would have long been a cure for depression; caveat -- sedatives can in fact worsen depression!