Adequate sleep could protect teenagers against depression. Those with set bedtimes are far less likely to suffer from depression or suicidal thoughts, according to a new study.
US researchers set out to examine the relationships between parental set bedtimes, sleep duration, and depression as a quasi-experiment to explore the potentially bidirectional relationship between short sleep duration and depression.
Short sleep duration has been shown to precede depression, but this could be explained as a prodromal symptom of depression. Depression in an adolescent can affect his/her chosen bedtime, but it is less likely to affect a parent's chosen set bedtime which can establish a relatively stable upper limit that can directly affect sleep duration, they said in their paper published in Sleep.
For their research the scientists looked at data from more than 15,000 adolescents and their parents in the U.S.
They found half of young adults had a set bedtime of 10pm, but a quarter were allowed to stay up past midnight and slept an average of 40 minutes less each night
The study, released in the journal Sleep, found sleep-deprived teens were 24 per cent more likely to suffer from depression and a fifth more likely to have suicidal thoughts.
"The results from this study provide new evidence to strengthen the argument that short sleep duration could play a role in the etiology of depression. Earlier parental set bedtimes could therefore be protective against adolescent depression and suicidal ideation by lengthening sleep duration," they observed.
Lead author James Gangwisch from Columbia University in New York, said: 'Our results are consistent with the theory that inadequate sleep is a risk factor for depression.
'Adequate quality sleep could therefore be a preventative measure against the illness.'
Professor Gangwisch added that a lack of sleep may affect how the brain responds to aversive stiumuli and hinder the ability to cope with daily stress. It could also affect judgement, concentration and impulse control.
The research, released by the American Academy of Sleep Medicine, reinforces NHS advice that teenagers need at least eight hours sleep per night. Yet recent research had found the UK's adolescents are getting less sleep than ever.
'The problem is that society has changed,' said Dr Paul Gringras, director of the Evelina Paediatric Sleep Disorder Service at Guy's and St Thomas' Hospital in London.
'Artificial light has disrupted our sleep patterns. Bright room lighting, TVs, PlayStations and PCs can all emit enough light to stop the natural production of melatonin.'
Other distractions include mobile phones and instant messaging, which teens may use well into the night.
'The early morning wake-ups for school mean they're not getting the average eight to nine hours of sleep,' Dr Gringras told the NHS.
'The result is a tired and cranky teenager.'