New research has revealed that our sleep patterns may not just determine what time we go to bed — they may also influence our personality and our levels of success.
Studies carried out in Germany show a more profound difference between night owls and early risers due to their preferred bedtime — it seems the brains of those who stay up late into the night are somewhat different to those tucked up by 10pm.
This preference for morning or evening is known as your sleep ‘chronotype’ – and according to the research, may even determine whether you demonstrate certain ‘dark’ personality traits. When scientists studied the brains of ‘late chronotypes’ or night-owls and ‘early chronotypes’ or larks, they found that the owls’ brains appeared to be less efficient in transmitting nerve signals than those of early risers.
Dr Jessica Rosenberg of the Institute of Neuroscience and Medicine in Jülich, Germany says: “Our results show that extreme ‘late chronotypes’ (night owls) show differences in the diffusion of water molecules in areas belonging to the white matter of the brain as compared to early and intermediate chronotypes (larks).”
This indicates a difference in the level of signal transmission, or communication between brain areas, she explains.
This could be linked to depression in owls, who suffer a kind of ‘jet lag’ by being forced to reluctantly participate in a world of early risers which is in conflict with their natural tendency to sleep late.
The fact that night-owls show a much larger ‘discrepancy’ than early risers between individual sleep preferences and normal work schedules can lead to what she calls “the accumulation of a substantial sleep deficit during the working week”.
And, as much research has shown, there are links between depression and lack of sleep.
Late-nighters may find their lifestyles bring on more than a case of the blues. Studies carried out at the University of Western Sydney reveal that a night owl is more likely to be narcissistic and more Machiavellian in their desire to manipulate others — and may even be more inclined towards callousness and insensitivity.
Other data shows night owls tend to have more extrovert personalities than the more conservative larks.
The apparent personality differences between night owls and larks may not be as straightforward as they might seem, cautions Dr Elaine Purcell, consultant in sleep disorder medicine at the Mater Private Hospital. It’s too early to talk about the influence of sleep patterns on personality, she believes, adding that more research needs to be carried out on this area.
Prof Richard Costello, consultant in respiratory and sleep medicine in Beaumont Hospital and president of the Irish Sleep Society, also questions any definite links between sleep patterns and personality traits.
“It wouldn’t pass what I’d call the common sense approach,” he says, adding that most research shows people are larks and owls partly due to habit, and partly because their sleep pattern is intrinsically biological — and that many of us can work around them.
“People can get up and get to the office early and they are working in the time zone that suits them — larks get to work early and get a lot of work done whereas night owls tend to struggle during the day and will often postpone a task until night when it suits them.”
However, he points out, once owls ‘recognise’ their individual body clock and understands how it works, being prepared to put in the extra work will help them achieve success.
However, the case with depression is somewhat different. If you’re an extreme night owl who finds it very hard to go to bed early, you’re going to be sleep deprived, says Dr Purcell.
And, as science has repeatedly shown, sleep deprivation will lead to depression and affect your mood so owls are more likely to suffer depression and seasonal affective disorder (SAD).
Sleep deprivation may also affect your achievement explains Dr Purcell. “In general it is thought that larks do better in school, college or the workplace because they are on time and alert and able to absorb information whereas the night owl has great difficulty getting up in the morning and is missing early classes so they are at a disadvantage when it comes to exams.”
However, nothing is absolutely certain — the question is whether delayed sleep patterns lead to sleep deprivation and thus bring on depression, or whether it is depression itself which is changing the body clock.
“There is a known association between depression and being a night owl, so does the body clock lead to sleep deprivation and bring on depression, or does depression itself change the body clock?” says Dr Purcell. “There is a lot of work going on here. We know that depression affects sleep but we know that the classic change in sleep pattern of a person with depression is early morning awakening so they will often awaken at 4am or 5am and stay awake.”
On the suggestion that night owls are more extrovert personalities she questions whether this is because, being up late and more likely to be socialising, the night owl is perceived to be more extrovert than the lark.
“Do they socialise more because they are extrovert or are they extrovert because they socialise more? If you’re a night owl who’s worried by all this should you attempt to metamorphose into a lark? It is possible to change your sleep patterns if they’re not too extreme,” says Dr Rosenberg. “There is a genetic disposition to be an early, late or intermediate chronotype.
“You can adjust your chronotype only in a certain time framework — according to social duties, such as school or work — but you can never turn an extreme night owl to into an early lark.”
Last summer Prof Kenneth Wright in Colorado proved that we can change our body clocks — he sent volunteers on a camping trip where artificial light was banned.
Researchers found the differences between early and late risers disappeared almost entirely when there was only natural light outside.
People went to sleep earlier, and over the week of the experiment, their body clocks moved to sleep earlier by two hours over the week.
While our circadian rhythm, or internal body clock might be something we’re born with, external influences or ‘zeitgebers’ can also have a major effect on our sleep patterns. “You cannot alter your genetic influences but you can alter your environment,” says Dr Purcell. “Social media and lifestyle play a very important role nowadays, so the extent of social media in people’s homes is artificially delaying their body clock.”
Change the external factors that may be pulling the strings to your circadian rhythm and you could change from a moderate night owl to one who is more open to the idea of rising earlier — and it could actually do you good.
“Many of our body processes are controlled by our body clock — hormone production, for example.”
Testosterone is produced on a Circadian Rhythm during sleep at night so sleep deprivation reduces testosterone production, she says.
There are many essential body functions that happen during sleep, which can be affected by sleep deprivation. “Sleep deprivation has lots of effects — for example, it can stunt growth in children, lower testosterone levels in men, reduce libido and increase blood sugar levels.
“It is linked to depression, there is increased risk of heart disease and blood pressure increases and more risk of being in a car accident.”
Prof Costello puts a mechanical spin on it: “Sleep is crucial to our well-being – that’s when the repair work is being done. Sleep is for repair and regeneration — resting or watching TV doesn’t do it.
“It’s like a washing machine with spin and rinse cycles — if it doesn’t work right, the clothes don’t come out clean.”
* You’re more partial to the idea of a midnight feast than to a big breakfast shortly after waking. You tend to either avoid breakfast or eat it later.
* You’re happier taking on major tasks later in the day – for example, you’d prefer to sit exams at 3pm than at 8am and you opt to schedule a demanding exercise session for the evening
Your mealtimes can be quite flexible.
* If you don’t have to get up the next day you’ll probably end up going to bed an hour or two later than normal
* You catch up on sleep at the weekend when you get up to two to three hours more sleep a night.
* You need the alarm clock to wake you up.
* You’re up early and your bed-times and rising times are roughly the same at the weekend and on weekdays.
* You feel peckish when you wake up and usually eat a hearty breakfast shortly after rising.
* You’re a creature of habit at mealtimes.
* You feel at your best in the few hours after waking up, and the day gradually goes downhill. Often you feel tired and ready to sleep by 9pm. Some scientists put this down to what’s called a “sleep pressure” that builds up as the day goes on.
* Where possible, you avoid disruption to your sleep pattern.
* Your preferred window for something demanding like exams or a tough exercise session is in the morning.