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Friends and family may marvel at the fact that you manage to wake at the same time every day – even when you forget to set your alarm.
But your ability to do this is one sign that your body clock – your circadian rhythm – is working as nature intended. Just as a flower opens in the morning and closes at night, circadian rhythm dictates that we too should rise with the lark, bursting with energy at the first sign of light.
But daylight isn't the only factor determining the natural sleep-wake cycle. Flowers start to open at daybreak even when they're subjected to constant darkness, and the human body clock is just the same, explains Sammy Margo, a chartered physiotherapist and author of The Good Sleep Guide.
Read on to learn all about your natural rhythm.
"Your body is programmed to run like clockwork, without exception. The hormones that regulate your patterns of sleep, hunger, and energy rise and fall at the same times in any 24-hour cycle," Sammy says.
"Nighttime is when bodily systems slow down so that all sorts of deep restorative healing processes can take place. Circadian rhythm doesn't adapt to the fact that you're a night owl, coming to life in the wee hours instead of giving in to sleep.
"If you happen to be active and working at a time when you should be resting, your body simply misses out on its healing processes, and that's why shift workers are unfortunately vulnerable to a litany of health problems."
"Your chronotype – whether you're an owl or a lark – is determined by a subtle difference in the length of something called your PER3: the body clock gene", Sammy explains.
"Larks have a healthy, longer-length PER3. But the shorter PER3 of owls is essentially a design fault. It is at odds with natural circadian rhythm and makes owls want to eat, sleep, work and rest at times when their hormone levels would favour them doing the opposite."
"It is during good-quality overnight sleep that our brains flush out the build-up of toxic beta-amyloid plaques associated with a higher risk of Alzheimer's," says Sammy.
"But regularly missing out on sleep – whether due to your owl gene, shift work, or the fact that you've been travelling across time zones – increases this risk.
"Sleep also governs the appetite-regulating hormones leptin and ghrelin. Missing out can cause the double whammy of increased hunger and a sluggish metabolism that leads to weight gain and obesity, with associated problems such as diabetes, heart disease and cancer.
"There's strong evidence linking low mood with poor-quality sleep, too, partly because you're inadvertently subjecting yourself to higher levels of the stress hormone cortisol when you don't get enough shut-eye."
Research shows that our gut microbiota (GM, the bacteria in your gut) has its own circadian rhythm, which is also affected by sleep, says Dr Megan Rossi, a registered dietitian and author of Eat Yourself Healthy.
"Just two days of sleep deprivation has been shown to impact our GM, which may explain why not getting enough sleep seems to exacerbate gut symptoms, particularly in people with irritable bowel syndrome (IBS).
"Interestingly, this relationship seems to be bidirectional, meaning that a disturbed GM may also lead to disturbed sleep. But in my clinical practice, I've found that simple dietary changes, such as increasing your daily range and number of plant-based foods, can boost shift workers' GM and, in turn, improve their sleep quality."
Focus on sleep for a happier, healthier circadian rhythm.
Start by waking yourself up for an early-morning walk. An early dose of daylight helps to balance your sleep-wake cycle, and your brain will thank you by preparing you for sleep 16 hours later.
If your home or workplace is dark, use a lightbox to trick your brain into being more lark-like.
Have supper early in the evening to avoid trying to digest food when your metabolism is shutting down.
Stick to a regular bedtime. Avoiding late night screen time and dimming the lights will boost melatonin and prepare you for sleep.
Keep cool at night (16-18°C) even if you’re wide awake – your body temperature should be coolest at 4am.
If you’re working a night shift have a nap before, and wear dark glasses to travel home afterwards (unless you’re driving). You’ll be more likely to sleep well even if it isn’t at the right time of day for your body clock.
Karen is a freelance health journalist and author/editor of 14 health books. She is a member of the Medical Journalists' Association and her features have appeared in various publications including Woman's Own and the Guardian.
Find out more about Karen Evennett.
Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn’t possible, supplements can help. This article isn’t intended to replace medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.