Jenni Murray, the doyenne of Radio 4’s “Woman’s Hour”, curses the fact that she was born at 10pm. She’s convinced that being born late in the day makes her an evening-loving owl rather than an early-rising lark.
“Getting up at 5.30am for work is absolutely not natural to me,” she said recently.
Fascinatingly, she claimed that everyone’s body clock is set to the time we were born.
“It’s a theory I heard years ago. I was born at 10pm and tend to be more alert late in the evening.”
The idea sounds like the stuff of old wives’ tales or woo woo astrology. But, in fact, Murray’s conviction is supported by an oft-neglected area of research.
Evidence shows that being a morning or an evening person does, indeed, appear linked to the hour of your birth.
It may also help to determine a wide range of other crucial characteristics, such as your intelligence and risk of becoming a criminal – even whether you may become depressed, have attention deficit hyperactivity disorder (ADHD) or are prone to developing diabetes.
The fact is that owls and larks seem to be equally divided across the population.
However, the bad news for people such as Jenni Murray is that being an owl forced to keep a lark’s hours may be seriously bad for one’s health. She might want to consider presenting an evening programme instead.
Despite the fact that being an owl or a lark appears to have fundamental health consequences, remarkably few researchers have investigated the relation between people’s time of birth and their mental and physical make-up.
However, 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: the students born in the morning scored better in the morning tests. Clearly, they were larks. Those born later did better in the late-afternoon exams, and thus were owls.
“Time of birth was significantly related to being a day person or a night person,” the scientists reported in the Journal of Social Psychology. “The results suggest a critical period for setting the biological clock for alertness may be the moment of birth.”
It seems the body clock may be set when a baby is first exposed to the light of the world. The nature or quality of the light they experience appears to help set their body’s clock for the rest of their life.
One clue to this is found among adults who were born prematurely. Studies show they are much more likely than normal to be ‘extreme’ larks, waking early, raring to go.
For example, a study of adults in their mid to late 20s by Dr Sonja Strang-Karlsson, a premature birth expert at Helsinki University, reports that those who were born as ‘very low birthweight’ babies naturally wake up on average 40 minutes earlier than anyone else.
Why are their body clocks so advanced? Light seems to play a crucial role. Twenty years ago, in neonatal intensive-care units, it was standard practice to leave bright lights on all day and night. This seems to have set the infants’ body clocks fast.
Only in more recent years have hospitals begun to turn lights on and off in the intensive-care units, to mimic the outside world’s natural body clock-setting rhythms.
Those extreme lark children should have little to complain about. As Dr Sonja Strang-Karlsson’s study concludes, “Morningness is associated with beneficial health outcomes.”
Annoyingly for sleepy-eyed night owls, their jealous suspicions about larks being super-efficient goody-goodies seem to be true. Researchers who studied 700 people aged from 18 to 32 have found morning people tend to be more persistent in pursuing tasks. They are also more resistant to fatigue and frustration, says Dr Ana Adan, the Barcelona University psychologist who led the study.
These characteristics make the lucky larks likely to experience high life satisfaction and low anxiety – which makes them significantly less likely to get mixed up with drugs, says the 2014 report in journal Personality & Individual Differences.
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’. The ancient Greeks must have noticed this, too.
The astrological texts they wrote 2,000 years ago say that people born under the sun were far better at practical and businesslike tasks.