EVER wondered why you are a morning person or why you function better late at night?
Well, chances are it’s linked to the time of day you were born.
A rising tide of scientific research suggests that whether you are a lark or owl, is determined by the hour you were born.
And, the time you entered the world could also help determine your intelligence levels and the health problems, such as depression or diabetes, you may suffer in your lifetime.
Around 15 per cent of the population are night owls and 15 per cent are morning people, with 70 per cent of people falling somewhere in between, sleep expert Professor Jim Horne told The Sun Online.
The theory goes that the time of day you are most alert is related to the time you were first exposed to light as a newborn.
While, evidence also suggests it may be determined by whether or not a baby is born prematurely.
A study of adults in their mid-to-late 20s, by Dr Sonja Strang-Karlsson, a premature birth expert at Helsinki University, found that those who were born as ‘very low birthweight’ naturally wake up on average 40 minutes earlier than anyone else.
Dr Strang-Karlsson’s study found “morningness is associated with beneficial health outcomes”, the Daily Mail reported.
But, unfortunately, for night owls it’s likely they have inherited the rawer end of the deal – you’re more like to burn out and suffer mood problems.
Research has found that night owls are more likely to be aggressive or antisocial in their youth and others are more likely to suffer from depression, develop addictive behaviours or develop ADHD (attention deficit hyperactivity disorder).
Barcelona University’s Dr Ana Adan says the fundamental problem may be caused by what is described as ‘social jet-lag’ — where one’s body clock runs at a different time to the demands of society.
Dr Adan said: “Evening-type subjects are well-known social jet lag sufferers, as they must develop a behavioural pattern in order to adapt to the social schedule.
“Several studies have linked different circadian rhythm genes with the development of mood disorders, schizophrenia and drug consumption.”
Dr Adan said when evening people struggle to keep up with a social schedule, they may develop symptoms like depression and anxiety.
And being a night owl could affect the structure of your brain.
Other studies have suggested night owls are likely to experience worse sleep and more tiredness during the day and consume greater amounts of tobacco and alcohol, while poor sleep is known to increase the risk of obesity.
Jessica Rosenberg at RWTH Aachen University in Germany studied this further.
Along with her colleagues, they used diffusion tensor imaging to scan the brains of 16 morning people, 23 night owls and 20 people who are somewhere in the middle.
They found a reduction in integrity in night owls white matter in the brain in areas associated with depression.
“We think this could be caused by the fact that late chronotypes suffer from this permanent jet lag.” said Rosenberg.
Aside from the mental impacts, there are the physical impacts of having to drag yourself out of bed at a time that does not suit your natural body clock – which can have a knock-on effect on your health.
A major study of more than 64,000 women reported last year that owls have a significantly raised risk of developing type 2 diabetes if they have to work shifts that start early.
The increased risk may possibly be due to long-term inflammation in the body, which is a known cause of type 2 diabetes.
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Such a condition can result from being chronically tired, so it is much healthier for owls to work shift schedules that match their body clocks, says the Harvard Medical School study.
It is not all doom and gloom though.
Studies have shown night owls tend to be more intelligent and more creative.
A survey of 420 people by Sydney University declared: “Contrary to conventional folk wisdom, evening types are more likely to have higher intelligence scores.”
Dr Adan’s study, which looked at the lifestyles and personality traits of 700 Spanish psychology students from two universities, found evening people tend to be more extravagant and impulsive “with a higher tendency to explore the unknown”.
The study originally appeared in a 2014 report in journal Personality and Individual Differences.
So what does being an early riser say about you and your health?
Surrey University’s Sleep Research Centre tips for a good night's sleep
- Try to go to bed and get up at the same time each day.
- Spend time outdoors. Natural light in the morning can help to synchronise the body clock
- Get regular exercise each day, but not just before bed.
- Make your bedroom restful. Maintain a comfortable temperature and keep noise down
- Only use the bedroom for sleep and relaxation
- Engage in stimulating activity just before bed – exercise, playing games, watching TV
- Drink caffeine or alcohol before bed
- Smoke before bed
- Go to bed hungry
- Nap in the evening
- Worry about your sleep – understand your sleep need and don’t set unrealistic expectations
Dr Adan found morning people tend to be more persistent at pursuing tasks and are more resistant to fatigue – making them the envy of most night owls.
This often translates to lower levels of anxiety and depression, unlike night owls, and higher rates of life satisfaction.
A similar study of more than 600 Britons, conducted seven years earlier by Surrey University’s Sleep Research Centre, concluded that morning people are simply “more conscientious”.
But there are ways you can maximise your potential if you know you are a morning person or an evening person.
If you are unsure you can take the Surrey University’s Sleep Research Centre test here.
In 2010, psychologists from Cleveland State University in Ohio gave large groups of students mental-performance tests in the morning and in the late afternoon.
The researchers then examined the students’ health records to see whether they were born in the morning or later.
The results matched and students born in the morning scored better in the morning tests, while those born later did better in the late-afternoon exams.
But sleep expert, Professor Jim Horne, cast doubt over the theories.
He said: “I’m afraid that I’m very doubtful about this correlation. Younger adults are more likely to be owls, and as we get older we become more lark like anyway.
“In general, owls are more adaptable than larks to changes in the timing of their sleep, as in jetlag and shift-work for example.
“Although being a lark or owl has some genetic basis, it is mostly nurture and one’s social and physical environment that has the greater influence.
“In fact, most of us are neither larks nor owls but lie in the middle of this continuum. There is no solid evidence that being one or the other is more liable to ill-health.”
But our tendency to be more alert in the morning or at night may also be determined by genetics.
In 2012, new research found identified a common gene variant that affects virtually the entire population, and which is responsible for up to an hour a day of your tendency to be an early riser or night owl.
The results appeared in the November 2012 issue of the Annals of Neurology, and found the gene determined preferred sleep times and peak cognitive performance times.
Dr Andrew Lim, lead author in the study, said: “Previous work in twins and families had suggested that the lateness or earliness of one’s clock may be inherited and animal experiments had suggested that the lateness or earliness of the biological clock may be influenced by specific genes.”
New technology in obstetric practices, however, are seeing more babies born in daylight and could mean an end to number of night owls in the population.
This could be done deliberately given the fact that there are higher rates of complications and death during birth on weekends and at night than during the day.
A study last year in the BMJ, by Imperial College London, warned that low weekend staffing levels could be responsible for an additional 770 babies dying and 470 mothers suffering infections every year in the UK.
Professor Paul Aylin, the senior academic on the research team, said: “More work needs to be done to better understand the causes of these differences, so that steps can be taken to improve outcomes for mothers and babies.
“Maternity care involves a whole team including midwives and other medical staff, so one avenue for future research might be to look at staffing levels beyond consultants.”