Working with your body clock for better health

Understanding your circadian rhythm can help you make healthier choices.

Health Agenda magazine
April 2018

Ever wondered why you can stay up through the night, yet your partner is yawning at 8pm? Or why some people are naturally chipper in the morning while others need caffeine? It’s all because of our built-in body clock, called circadian rhythm.

Our circadian rhythm is controlled by a gene that produces a protein that accumulates in our cells during the night, and degrades during the day. This means the protein levels change during a 24-hour cycle, linked to our circadian rhythm.

What’s circadian rhythm?

Circadian rhythm is the cycle that tells our bodies when to wake up, eat and sleep, and even motivates us to exercise. It’s synced to environmental factors, like sunlight.

This is why our health, sleep cycle, mood and hunger pangs can be affected when there’s a difference between our external environment and internal biological clock. Jet lag is one example of how your body clock is affected.

Experiencing jet lag is just the tip of the circadian clock iceberg – the clock also regulates critical functions such as hormone levels, sleep and metabolism.

How your body clock affects your sleep

Despite the predictability of our own clocks, we don’t all tick at the same time. This is now thought to be genetic, and explains why everyone in some families can be night owls or early risers.

We all have an individual internal clock, and it’s smart to listen to it. Not having a regular routine can make it hard to get to sleep. And if you sleep during the day it tends to be a lighter, more disturbed sleep.

How to get quality sleep

• Set your bedtime to ensure you get 7 to 9 hours sleep a night.
• Avoid caffeine close to bedtime as this may impact your ability to fall asleep.
• Change the lightbulbs. A dimmer light in your bedroom can help you avoid being kept alert when it’s time to go to bed.
• Keep electronic devices out of the bedroom. If you must use an electronic device at night, set the screen to the ‘blue’ or ‘night’ shade in settings or install a program called F.lux to do this for you. Ideally avoid devices an hour before bedtime.

For more healthy sleep habits, visit the Sleep Health Foundation.  

Best time to eat?

Dr Tamara Varcoe, postdoctoral research fellow at Adelaide Medical School, says there has been “a stack” of research linking metabolism and food intake timing.

“Metabolism functions change over 24 hours. We’re designed to eat during the day so all the processes that occur when you eat are more effective during daytime.”

Those who can’t sleep at night, such as shift workers or frequent travellers, are in the most affected category.

As Varcoe says, “These people are more at risk of developing disorders such as diabetes, being insulin resistant and being overweight. We’re designed to be awake and eat during the day, and sleep at night. As soon as you begin to mess with that, problems are invited in.”

The advice? If you’re a night-time sleeper, since the body changes the way it handles digesting and metabolising food as night gets closer, ensure that your breakfast and lunch are substantial, and keep your evening meal smaller.

If you’re a night owl, frequent flyer or shift worker, the research shows that maintaining a regular schedule of eating and sleeping is important. The Sleep Foundation also recommends eating small, frequent meals and having a stock of healthy snacks so when you’re tired you don’t opt for fast food.