Morning people have few problems springing out of bed bright and early to face the day.
Now it has emerged they are less likely to suffer from depression and are generally happier too.
A study has found morning ‘larks’ are up to 35 percent less likely to suffer from depressive symptoms, based on their genes.
These people, who are more likely to be older and female, also have better wellbeing.
The silver lining for night owls is their ‘late riser’ genes may also make them more intelligent, perhaps because they spend more time reading when they are up late.
Scientists have discovered 327 new genetic regions which determine whether people are ‘larks’ who get up early in the morning or ‘owls’ with later bedtimes who naturally lie in for longer.
They have found for the first time that larks and owls may process caffeine differently, so that a morning cup of coffee may stay in a night owl’s system for longer and keep them up at night.
While shift workers who work at night were already known to be more prone to depression, this is the largest genetic study to find those with night owl genes are more at risk.
Professor Mike Weedon, of the University of Exeter Medical School, said: ‘The large number of people in our study means we have provided the strongest evidence to date that “night owls” are at higher risk of mental health problems, such as schizophrenia and lower mental wellbeing, although further studies are needed to fully understand this link.’
Dr Sam Jones, of the University of Exeter, said: ‘The link with depression could be explained by the fact that night owls are forced by their jobs and everyday life to get up early.
'Constantly having to fight against your natural body clock could have negative effects on your mental health.’
Experts believe around 15 percent of people are night owls, another 15 percent are larks and the rest of us are morning or evening types to a lesser degree.
The largest genetic study of people’s body clocks took in almost 450,000 British people from the UK Biobank genetic database and close to 250,000 people from the US who had used genetic testing service 23andMe.
Scientists found 351 genetic locations thought to make people early or late risers, of which 327 were previously unknown.
People with ‘lark’ genes appeared up to 11 percent less likely to be schizophrenic and had up to a third lower risk of depression.
The larks’ genetic profiles were compared to those of people in a previous study on wellbeing and happiness.
This showed larks were significantly more likely than night owls to be content with their lives.
The findings, published in the journal Nature Communications, show for the first time that night owls have differences in their genes which are also linked to intelligence.
Some night owl genes are active in the retina and the part of the brain which detects light.
Researchers now suspect night owls may be kept awake more by the artificial light in our homes, which may affect their eyes differently and disrupt signals to the brain telling them it is night-time.
The experts do not yet know how genes for light recognition and caffeine metabolism differ in larks and owls.
But the differences they have found suggest night owls could be more strongly affected by caffeine, so it wakes them up more or lasts longer in their system, making them sleepy later on.
The findings show at least 13 percent of whether someone is a night owl or morning lark is inherited from their parents.
However the study found no link between night owl genes and obesity and type 2 diabetes, despite previous evidence.
The findings could lead to drugs to help people avoid depression, and sleep earlier, by blocking troublesome genes.