Circadian Rhythm

There is a time for everything

Our bodies have their own biological clocks. Everything is timed and controlled by natural biorhythms down to the cellular level. Our body’s internal clock sends signals to many different parts in the body, affecting things like digestion, the release of certain hormones, body temperature, and much more.

Our clock maximizes the function of every organ down to the cellular level. There is an optimal time for every physiological process from the utilization and storage of energy to repairing damaged cells. Our clock allocates every single one of these task to an ideal time of the day or night.

External Cues
  • Light (Natural & Artificial(blue)

  • Exercise/Activity

  • Eating/Drinking

  • Social Activity

  • Pharmacological


The release and activation of various hormones are a large part of how our biological clock exerts control over our physiology. Our bodies master clock (suprachiasmatic nucleus nucleus) is located in the hypothalamus. They hypothalamus is responsible for creating or controlling many hormones in the body. 


Here are some of the main hormones involved. Though there are many more. 

  • Melatonin 

  • Cortisol

  • Leptin/Ghrelin

  • Insulin

  • Growth Hormones

These are just some of the hormones involved and their roles vary. The most identifiable effect they have is on our sleep/wake cycle, utilization of energy and feelings hunger/satiety.

We are all shift workers

Chances are if you are teaching, you are getting up before 5am. This is a circadian disruption.

The symptoms of shift work disorder include:

  • Excessive sleepiness when you need to be awake, alert, and productive.

  • Insomnia, or the inability to sleep when you need to. This can mean trouble falling asleep, or waking up before you’ve slept sufficiently.

  • Sleep that feels unrefreshing or insufficient

  • Difficulty concentrating

  • Lack of energy

  • Irritability or depression

  • Difficulty with personal relationships

  • Weight Gain

  • Immune system suppression

  • Gastrointestinal problems

Challenges unique to our profession.

  • Working out of our time zone.

  • Lighting for class

  • Use of Technology/Apps/Screens

Factors that determine individual impact of shift
  • Rotating or irregular shift One of the perks of being a teacher is you can set your own schedule, this can be a double edge sword. New teachers can be hit especially hard by this because they are at the mercy of the booking gods. Often out of desperation they will open up many slots and end up with a scattered scheduled with gaps and holes everywhere it is easy to end up working split shifts.

  • Length of Shift Full time, part time or over-time?

  • Night Shift vs Swing vs Early Morning Depending on time zones and when you choose to work. Most people it would seem are waking up early. Others work through the night. Still others may have a situation where they work very late into the night and go to bed late. 

  • Consecutive Days How many days do you work without a day off?

  • Genetics Different individuals express genes differently and thus will have slightly different rhythms and sensitivities.

  • Age as we age our rhythm changes. Like most things it's not for the better.

  • Health Other comorbidities and illness will make you more prone to the negative effects of shift work disorder and the circadian disruptions can likewise worsen your illness.

  • Fitness. As usual, being physically fit protects us.

  • Diet. You are what you eat, no getting around that. It's a bit of a compouding factor because working brutal hours also makes you want to eat like crap.

Attitude is not a factor!! You can love a job all you want, find your why and feel all the job satisfaction in the world. That will not protect you, it is not an intervention. It might keep you motivated to continue a while longer. Just because someone is feeling the effects of shift-work does not mean they don't love their job.

Impact on the family.

Loved ones will try to wait up for you and keep you company. This impacts their health as well.

What can you do?
  • Sleep at regular times even weekends.

  • Keep Sleep Environment Dark

  • Time Restricted Eating

  • Eat Healthy Foods

  • avoid coffee after 12pm

  • Medications as prescribed

  • Exercise

  • Limit Blue light exposure at night

  • Get Natural Light during the day.

The information on this website is for general information purposes only and is not intended to diagnose, treat, prevent, or cure any disease.

The sole purpose of this site is to serve as a resource of online ESL teachers. To educate and promote safe occupational health measures that to enhance the teaching experience.