Phoebe Seymour discovers how our circadian rhythms can affect our sleep, mood, weight and wellbeing.
It’s ironic that something as natural to humans as sleep can be so unattainable. The wellness industry is booming with everything from natural remedies such as lavender sprays and CBD oils, to new technology including lightbulbs and smart watches to help us keep track of our sleep patterns.
The Global Wellness Summit 2020 reported that the world’s ‘sleep economy’ is set to reach $585 billion by Yet, around one in three of us struggle to sleep through the night, while one in ten toss and turn with insomnia. So why are we still struggling to sleep?
It seems that up until now, the wellness industry has been trying to tackle the symptom, not the cause. Could it finally be time to fix our sleep cycles? The Global Summit seems to think so. Their Future of Wellness 2020 report revealed we will soon see a ‘shift from sleep to true circadian health’ solutions.
What is a circadian rhythm?
From the Latin words circa meaning ‘around’ and dies meaning ‘day’, a circadian rhythm is a 24-hour cycle that affects the physiology of the human body.
A circadian rhythm not only regulates sleep, but other critical functions such as behaviour, hormone levels, body temperature and metabolism.
Scientists have been aware of this internal clock and how living organisms adapt to their external environment for many years, but it is only recently that they have pin-pointed how the body does this.
The ‘clock gene’ was discovered in the 1970s, before Nobel Prize 2017 winners Jeffrey C. Hall, Michael Rosbash and Michael W. Young discovered a gene that releases ‘period proteins’ into our cells. These proteins accumulate at night and lessen during the day, to control our biological rhythms.
This means our cells are able to calibrate to our circadian rhythms, and our physiology reacts to certain phases of the day. For example, our bodies release cortisol around 6am, to give us a boost in the morning, and secrete melatonin to prepare us for sleep at night.
Light up your life
Though the human body has evolved to prompt us when to be active and when to go to sleep, it is also very sensitive to light.
“The absolute key to healthy sleep and circadian rhythms is stable, regularly-timed daily light and dark exposure – our natural daily time cues,” says Dr Steven Lockley, associate professor of medicine at Harvard, and one of the world’s top circadian rhythms and sleep experts. “Sleep negates light input to the brain, and so keeping a regular sleep pattern will also help maintain regular light-dark exposure.”
This sounds simple, but with our 21st century lives centred around working on computers, binging on box sets and scrolling through our phones before bed, our digital habits could be stopping our bodies from running like clockwork.
“After dusk, when natural light disappears, we must minimise the negative impact of man-made light.” Dr Lockley continues, “In the day, we have evolved to be in the light, ideally sunlight, but if not, high quality blue-enriched indoor light.”
Getting outside for some natural light in the day and turning our phones off long before bed time, are therefore the simplest ways to help support circadian rhythms.
You are when you eat
It isn’t just light that helps our cycle stay on track, but our eating habits. While other diets concentrate on what we eat, circadian diets are all about when we eat.
Researchers at Harvard University and the University of Murcia found that early eaters lose 25 per cent more weight (and faster) than late eaters, while Hebrew University studies show that synchronising mealtimes with our circadian rhythms leads to more weight loss and reduced insulin resistance, compared to eating the same food without a schedule.
This means our cells are able to turn glucose into energy more efficiently, helping us perform better in the day. They concluded that a larger breakfast, a medium-sized lunch and small dinner helps us function best. Breakfast really is the most important meal of the day.
A study of clock genes in 2019, by John O’Neill, molecular biologist and principal investigator at the MRC, found that exposure to light (and cortisol production) needs to happen before breakfast. He demonstrated how insulin resets circadian clocks by increasing period protein synthesis. We therefore need light before we take our first bite, to achieve an optimal circadian rhythm.
“To be healthy, all of the clocks throughout the body, in every individual cell, have to be synchronised with each other, and then they have to be synchronised with the external world,” says O’Neill. “It’s the relative timing of when you see lights and have a meal, that is the thing that will help you reset as quickly as possible.”
While sleep is key to a long and healthy life, it’s not enough to get a good night’s slumber. We have to understand our internal clock and create the best external conditions possible, as well as fuelling our bodies with food at the appropriate times every day, in line with natural light.
“Circadian health optimisation – incorporating the type and timing of light – will become more important than ‘sleep’ in health and wellness within the next few years,” concludes Dr Lockley.
So, if you feel out of balance, you struggle with weight gain or your sleep routine is all over the place, you might just need to reconnect with that all-important circadian rhythm to get back your zen.