If you're working in a position that doesn't fit your inner clock, think about whether there's a way to make a change somehow. (Stock photo)

Waking up at 7am every day? I know what you're thinking: "Dear spoiled millennial, what's your problem? A lot of people get up much earlier than that every day and they never complain."

But don't be so quick to judge. Listen to my story first.

I'm a meticulous sleep planner. In the evening I calculate when I have to go to bed, so that I can get at least eight hours of sleep – nine is even better. I hardly nap in the afternoon and I rarely sleep in on weekends, even if I did celebrate for a bit too long the night before.

All this to say I'm a habitual person. I wake up at the same time every day. And this time is 8 o'clock.

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When my alarm rings at 8am, I jump out of bed. I never press the snooze button and I am usually out of the house within half an hour. When I started working at 23, my sleep rhythm fitted perfectly into my working day. I had to be at work between 9am and 9.30am and I was usually there at 9am sharp.

It all fitted together so perfectly that I took it for granted, I didn't know how fortunate I was. Then, after three years, I decided to change jobs. My new employer told me during the interview process that it was normal for everyone to be in the office at 8am.

I thought that everything had worked out so well for being at work by 9 o'clock for all these years, that it would probably work out just as well for 8 o'clock.

ONE YEAR OF JETLAG

But it didn't. When the alarm clock rang at 7am I felt as if I had taken part in a wrestling match overnight. The snooze button was my new best friend. Although I tried my best to go to bed before 11pm each day, I was tired every day and all day. On the weekends I suddenly slept until noon to make up for the sleep deficit from the week.

On some days my work routine ran like a blurred film in front of me. I felt like I had jet lag. But I felt that every day. I was in permanent jetlag.

I thought it would get better after a few months, but it didn't.

In March, after less than three months, I had to take three sick days. I had a cold. Nothing unusual in and of itself, but for those three days I slept nearly the entire time. In April, I was ill for another week, in May another week, again in June and July, and so on. In October, it got so bad that I had to stay home for a couple of days during multiple weeks.

I'd had a constant cold since March and been plagued by headaches again and again. I had taken more sick days in one year than I had during my entire career up until then.

THE SMALL, SUBTLE DIFFERENCE OF ONE HOUR

At some point I realised this pattern was nothing new. When I was in school, getting up at 7am had been horrible. My mother often had to wake me up three times just to get me out of bed. And when my parents weren't at home I'd sleep late.

I liked school and was always a good student, but to this day I still feel bad when I think about it.

The fact is, I'm not meant to get up at 7am. It's only a one-hour difference between 7 and 8am, but, for me, it's the difference between wellbeing and illness. And no one can blame me for not trying.

This all became clear to me when I began work in a role where I could go back to getting up at 8 o'clock most days. It's a privilege of my profession that I can choose. Many workers can't choose.

I'M A BEAR

Research continues to show that people have different inner clocks. One researcher differentiates between larks (early risers) and owls (late sleepers), and the psychologist Michael Breus has identified four so-called chronotypes: lions (early risers), bears (classical day-night rhythm, need eight hours of sleep every night - that's probably me), dolphins (light sleepers), wolves (late sleepers).

German researcher Till Roennberger, who is doing research on chronobiology at LMU University Munich, believes that people's daily routine usually need to coincide with their internal clock.

"If the schedules imposed by society do not correspond to individual sleep preferences, the differences between the expected sleep patterns on working days and those dictated by the internal clock lead to 'social jetlag'," Roennberger said.

When your alarm clock goes off, your body is still releasing the sleep hormone melatonin. This can have far-reaching consequences over time. According to a 2012 study published in the journal Current Biology (which Roenneberger also worked on), more than two-thirds of the Western population suffer from at least one hour of "social jetlag".

A recent study by the University of Arizona, published in the journal Sleep suggests that every hour of social jetlag increases the risk of heart disease by 11 per cent.

DO WE REALLY HAVE TO BE AT WORK AT 8AM?

The solution to this dilemma is relatively obvious in some industries that can change their start times. But for some sectors it's much more difficult. A doctor needs to be available when a severely injured patient is admitted to hospital, even if it is 7am.

But in many offices, there is no reason that everyone must be present at 8am or 9am, other than the argument: "That's the way it's always been."

In 2015, a speech by Oxford researcher Paul Kelley caused a stir when he said that teenagers should start school at 10 or 11am. This change could help some teens avoid exhaustion, anxiety and weight gain, he said.

"We can improve the life of a whole generation," Kelley said. Unfortunately, how a change like this could be implemented is not yet clear. Many employers still adhere to the 9-to-5 model, so parents need to be able to drop children at school at 8.30am to make sure they get to work on time.

YOU CAN DEFEAT THE SOCIAL JETLAG

If you feel that you're working in a position that doesn't fit your inner clock that it makes you sick, think about whether there's a way to make a change somehow - whether it's by talking to your employer, changing jobs or maybe even changing industry.

Kenneth P Wright, a researcher at the University of Colorado Boulder, did find in one study that social jetlag could be repaired. Wright had participants sleep in nature for a whole weekend, without an alarm clock. Participants not only felt better but the body released melatonin earlier in the evening and morning, allowing them to sleep earlier and wake up more refreshed.

I can't prove scientifically that I've been better since I don't have to get up at 8am, but one number speaks volumes.

In the last year, I took just one sick day.

- Business Insider