Circadian rhythms understanding and optimising your body's natural clock
- scotteckett
- Feb 3
- 9 min read
Updated: Feb 4
In our fast-paced world, sleep often takes a backseat to passing exams, working night shifts, or catching up on our favourite series, which can disrupt our internal clock. However, a nocturnal lifestyle can leave you confused, exhausted, and unwell. This is because humans and most creatures on Earth have a unique biological system that keeps our bodies in sync with the cycles of day and night—our circadian rhythm, which is influenced by our internal clock.
What Are Circadian Rhythms?
The word "circadian" comes from the Latin terms circa (meaning "around") and diēm (meaning "day"). Circadian rhythms influence everything from eating and sleeping to reproductive behaviours. Our internal circadian rhythm is synchronised to the sun's rising and setting, and many of our organs are attuned to the presence or absence of natural light, which serves as a cue for our body clock.
The primary regulator of the circadian rhythm is a group of cells called the suprachiasmatic nucleus (SCN), acting as our master clock. This structure is part of the internal body clock that regulates various physiological processes. the hypothalamus, located in the brain. The SCN is connected to the optic nerve, which allows it to respond to light and darkness.
For example, when you wake up in the morning, the optic nerve detects light, which triggers the SCN, our body's master clock. The SCN then sends signals to nearly every organ in the body, causing effects such as increased body temperature, heart rate, and blood pressure, and delaying the release of melatonin (the sleep hormone).
We tend to be most alert and focused in the morning, and cognitive performance is typically better early in the day due to our master clock. As the sun sets, the SCN detects darkness, prompting our organs to wind down—blood pressure drops, body temperature decreases, and melatonin is produced to prepare us for sleep in accordance with our natural circadian rhythm.
What problems does disrupting the body clock cause?
Disrupting your circadian rhythm affects multiple body systems since most cells contain internal clocks synchronized to your brain's master internal clock. While short-term disruption causes immediate effects like poor concentration and fatigue. Chronic disruption (common in shift workers) has more serious consequences. Research shows it increases the risk of metabolic disorders, cardiovascular disease, and type 2 diabetes by affecting insulin sensitivity and hormone regulation. Studies link it to weakened immunity, mental health issues like depression and anxiety, and potentially accelerated ageing. This occurs because the disruption throws off essential hormones like melatonin and cortisol that regulate many body functions.
How to identify your body's biological clock?
Your biological clock can be identified by observing your natural energy patterns and physiological indicators. The most reliable signs are your natural sleep-wake preferences - when you feel sleepy and wake without an alarm. Other key indicators include your body temperature rhythm (lowest around 3-4 AM), hunger patterns, and mental alertness peaks. Research shows these patterns are partly genetic, determining if you're a ''morning lark,'' ''night owl,'' or somewhere in between. To identify your rhythm, track for 1-2 weeks when you naturally: feel sleepy, wake up, experience peak alertness, and get hungry - ideally during a holiday when you're free from work/social schedules. Your temperature, cortisol (highest in the morning), and melatonin (rises in the evening) also follow this internal clock, and these require medical testing to measure accurately
The Importance of Maintaining Your Natural Rhythm
Scientists have found that disrupting the circadian rhythm can lead to insomnia, daytime drowsiness, disrupted sleep, and reduced productivity. Unfortunately, the consequences of circadian disruption can be much more serious, affecting both sleep and recovery.
Numerous studies have linked abnormal circadian rhythms to the following conditions:
Diabetes
Hypertension
Heart disease
Sexual dysfunction and low testosterone levels
Dementia
Obesity
Mood swings
Poor mental health
Understanding these potential health consequences is crucial. Just imagine what that sneaky bad habit of staying up late is doing to your body! The good news is that many of these issues can return to normal when you restore your natural rhythm
Common Disruptors of Circadian Rhythms
Screen Time and Blue Light
Over the past decade, nearly everything has gone digital, including activities like reading, which are now commonly done via electronic devices that emit artificial light. While technology has brought many benefits, it also comes with certain drawbacks.
Research has shown that the human eye is particularly sensitive to the blue light emitted by electronic devices like phones, tablets, and laptops. Exposure to blue light can suppress melatonin production, causing a shift in regular sleep patterns.
One study found that participants who used an iPad before bed took an average of 10 minutes longer to fall asleep, had less deep sleep, and took longer to feel fully awake the next morning compared to those who didn't use the iPad.
Noise
Some people can sleep through noise, as the brain can filter unnecessary sounds, but this can still affect their sleep and recovery. However, not all noises are equal. For example, the steady hum of an air conditioner may not disturb you, but sudden sounds—such as a phone notification—can disrupt your physiological processes related to sleep.
Moreover, research has found that meaningful noises, like conversations, are more likely to wake you up. Noise can reduce sleep quality, further disrupting your internal body clock and sleep cycle.
Circadian Rhythm Fasting: Time-Restricted Eating for Better Sleep and Health
This emerging approach to eating aligns your meal timing with your body's natural internal clock. Here's what you need to know:
What Is It?
Circadian rhythm fasting means eating within a specific window (typically 8-12 hours) that matches your body's natural daily rhythms. Unlike other fasting methods, the focus is on when you eat, not just what you eat.
The Science Behind It:
Your digestive system has its own internal clock that:
Processes food most efficiently during daylight hours
Reduces insulin sensitivity at night
Optimises metabolism when eating aligns with natural light cycles
Key Benefits:
Better sleep quality
Improved digestion
Enhanced energy levels
More stable blood sugar
Potential weight management support
How to Start:
Track when you naturally feel hungry
Begin eating within 2-3 hours of waking
Stop eating 3-4 hours before bedtime
Maintain consistent meal times
Important Note:
Research shows eating late disrupts sleep quality even if you're not aware of it. The ideal eating window typically ends by 7-8pm for most people who sleep around 10-11pm.
Who Should Be Careful:
Pregnant women
People with diabetes
Those with a history of eating disorders
Shift workers (may need modified approach)
Pro Tip: Start gradually by reducing your eating window by 30 minutes each week until you reach your target window.
How to Get Back to Your Natural Rhythm
Now that we understand the importance of maintaining a healthy circadian rhythm and what can disrupt it, let's explore some strategies to help you get back on track with your sleep phase.
1. Manage Light Exposure
During the day, expose yourself to bright light, preferably natural sunlight. This helps reinforce your body's natural wake-sleep cycle.
In the evening, reduce exposure to blue light from screens to improve your sleep hygiene. Consider using blue light filtering apps or glasses, or switch to reading physical books before bed.
Keep your bedroom dark at night to support your internal clock. Use blackout curtains or an eye mask if necessary.
2. Create a Consistent Sleep Schedule
Try to go to bed and wake up at the same time every day, even on weekends, to maintain a consistent sleep-wake cycle and support good sleep hygiene.
Establish a relaxing bedtime routine to signal to your body that it's time to sleep. This could include reading, taking a warm bath, or practising relaxation exercises.
3. Optimise Your Sleep Environment
Keep your bedroom cool, but not so cold that you're uncomfortable, as temperature can affect your body clock. If it's winter, use blankets to stay warm without overheating, as temperature can impact your sleep cycle.
Minimise noise in your sleeping area to support your natural circadian rhythm and enhance your sleep and recovery. If you must sleep in a noisy environment, consider using earplugs to help block out disturbances and improve your sleep hygiene and overall sleep habits.
Invest in a comfortable mattress and pillows to ensure you're physically comfortable (this plays a crucial role) during sleep.
4. Be Mindful of Diet and Exercise
Avoid caffeine and heavy meals close to bedtime to maintain stable hormone levels and support your sleep cycle and quality of sleep.
Regular exercise can improve sleep quality but try to finish your workout at least a few hours before bed.
Consider timing your meals to support your circadian rhythm. Eating larger portions at breakfast rather than dinner may lead to better blood sugar control and support weight management, aligning with your natural circadian rhythm and overall sleep and wake patterns.
5. Consider Supplements
Several supplements can support healthy circadian rhythms and improve sleep quality. Always consult with a healthcare professional before starting any new supplement regimen.
Melatonin
Melatonin is a hormone naturally produced by your body to regulate sleep-wake cycles and support your circadian clock, influencing your hormone levels. A recent study found Research shows that supplementing with 3 mg of melatonin helped night-shift workers reduce circadian misalignment by 20% and improved weight and BMI, highlighting its role in managing sleep disorders.
Magnesium
Magnesium is another key nutrient that supports healthy circadian rhythms. It helps calm the brain by reducing nerve cell activity, which can promote better sleep. Foods rich in magnesium include pumpkin seeds, almonds, spinach, cashews, peanuts, and dark chocolate.
Vitamin D
Research shows that low vitamin D levels are linked to poor sleep quality, and supplementing with vitamin D can help synchronise circadian rhythms. The best source of vitamin D is sunlight, so try to get outdoors during the day. If you live somewhere with limited sun exposure, you may want to consider a vitamin D supplement.
While these strategies can be highly effective, some individuals may benefit from more personalised guidance. If you're struggling to reset your circadian rhythm and improve your sleep quality, consider exploring our holistic adult sleep coaching course. Our experienced coaches can provide tailored advice and support to help you optimise your sleep patterns and overall health.
The Role of Diet in Circadian Rhythms
Did you know that circadian rhythms play a role in regulating hormones that control blood sugar? If you eat the same amount of food each day but consume the majority of it at breakfast rather than dinner, you may see better blood sugar control.
This is because hormones like GLP-1, which regulate blood glucose, are more active in the morning, aligning with our body's internal clock. Studies have found that people who eat larger portions at breakfast have better glucose control than those who eat large meals at night.
Heavy dinners can also negatively impact digestion and sleep, disrupting your natural circadian rhythm. increase the risk of obesity. By shifting more of your food intake to the morning, you'll not only support your circadian rhythm but also improve your weight and blood sugar levels, aiding digestion.
Conclusion
The science of circadian rhythms and sleep is complex, and even scientists don't fully understand all aspects of it. Why do we need sleep in the first place to maintain our sleep cycle and support our overall health? Perhaps it's because sleep is our body's deepest state of regeneration and recovery, but many questions remain unanswered.
What we do know for certain is that sleep is essential for maintaining a balanced circadian clock. Sleep deprivation and circadian rhythm disruptions can lead to long-term health problems such as obesity, diabetes, and sexual dysfunction, affecting various physiological processes. By understanding your circadian rhythm and taking steps to support it, including proper sleep habits, you can significantly improve your overall health and well-being.
Remember, restoring your natural rhythm is a process that may take time, especially if you have experienced disrupted circadian cycles. Be patient with yourself and consistently apply these strategies to help reset your internal body clock and improve your sleep habits. Over time, you should notice improvements in your sleep quality, energy levels, and overall health, positively impacting your metabolic functions and supporting your biological clock.
Have you experienced circadian rhythm misalignment due to being a night owl? How did it affect you, and what strategies did you find most helpful in combating it, considering your internal circadian clock? Share your experiences in the comments below—your insights could help others on their journey to better sleep and health!
As always, stay tuned for more health and well-being articles related to sleep, the 24-hour cycle, and managing jet lag. Sweet dreams, and remember to prioritise your sleep hygiene for better rest!
While these strategies can be highly effective, some individuals may benefit from more personalised guidance. If you're struggling to reset your circadian rhythm and improve your sleep quality, consider exploring our holistic adult sleep coaching. Our experienced coaches can provide tailored advice and support to help you optimise your sleep patterns and overall health. Want to learn more about your sleep? Take our free Epworth Sleepiness Scale to assess your daytime sleepiness: Epworth Sleepiness Scale | evolution Fitness
More information on sleep health?
National Sleep Foundation: (sleepfoundation.org)
Sleep Education (American Academy of Sleep Medicine): (sleepeducation.org)
National Institutes of Health (NIH) - Sleep: (www.nih.gov/health-topics/sleep)
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