Late nights in the genes
By Roger Highfield, Science Editor
(Filed: 16/06/2003)

The reason that some people like to burn the midnight oil could be due to their short genes, scientists reported yesterday.
Although most people know instinctively if they are owls or larks - or an 'evening' or 'morning' person - scientists have now found a genetic explanation.
A correlation between a difference in the length of a so-called clock gene and being a night owl was described yesterday in the journal Sleep by a team from the University of Surrey, St Thomas's Hospital in London, and Holland.
The gene, Period 3, forms part of our internal body clock, and comes in two variants, one short and one long. Dr Simon Archer, lead author, said: 'We discovered that the shorter variant of the gene is significantly more common in people with an extreme evening preference.
'This is even more so in patients suffering from delayed sleep phase syndrome, a sleep disorder where people fall asleep at very late times and have difficulty waking up in the morning.' Prof Jo Arendt, senior member of the team, said: 'It is tempting to speculate that one day some people might choose their lifestyle according to their clock genes.'
Another co-author, Dr Malcolm von Schantz, added: 'There are at least 10 of these clock genes. Whether you are a night owl or a morning person is determined by the sum of the differences between them.'