Our bodies are intrinsically regulated by a natural internal clock known as the circadian rhythm, which controls various physiological processes, including the sleep-wake cycle, immune function, temperature, elimination, digestion, certain hormones and stress response. Hormone cortisol spikes in the morning to wake us up, boosting alertness in the late morning, and melatonin is secreted around 9 p.m. to help us fall asleep. This master timekeeper is composed of about 20,000 neurons; it is driven by an internal clock located in the brain's suprachiasmatic nucleus (SCN), a small group of cells in the hypothalamus. The SCN receives signals from the external environment, such as light exposure, which helps synchronize the circadian rhythm with the external day-night cycle.
How Does Circadian Rhythm Work?
The circadian rhythm works through a complex network of cellular and molecular processes that occur throughout the body. When exposed to natural light during the day, the SCN sends signals to the rest of the body to be awake and alert. In contrast, in the absence of light during the night, the SCN triggers the release of melatonin, a hormone that promotes sleep. At the cellular level, the circadian rhythm is regulated by a group of proteins called clock genes. These genes interact in a feedback loop, producing proteins that rise and fall in a cyclic pattern over 24 hours. This molecular clockwork helps regulate the timing of various physiological processes in different organs and tissues throughout the body, keeping them in sync with each other and with the external environment. The way we work and our modern lifestyle increasingly disrupts our inner clock. Ever since Thomas Edison patented the light bulb in 1879, we have lived in a world of never-ending bright light. We can do whatever and whenever we want; dancing till 3 a.m., dinner at 10 p.m., working on your presentation till late at night. No problem at all. But when our lifestyle doesn’t sync with our inner clock, it impacts our wellbeing and results in many health issues. A study published in the International Review of Psychiatry linked circadian rhythm dysregulation with an increased risk of cardiovascular disease, cancer, depression, diabetes, bipolar disease, obesity, ADHD and schizophrenia. Research in the Annals of the New York Academy of Sciences found that our inner clock misalignment triggers metabolic, autoimmune and mood disorders. I think we can all agree, it is super important to take action to avoid anything that disrupts our 24-hour clock.
Now let’s look at some factors that can change the circadian rhythm and how to get back on track.
1. Light and Darkness: Light is one of the most significant environmental cues that can affect the circadian rhythm. Exposure to light can help reset the internal clock and promote wakefulness, while darkness promotes sleep. This is why it is essential to maintain a consistent sleep schedule and avoid exposure to bright light in the evening, such as from electronic devices.
2. Shift Work: Working night shifts or rotating shifts can disrupt the body's internal clock and lead to irregular sleep patterns. This can have significant health consequences, such as increased risk of obesity, diabetes, and cardiovascular disease. To mitigate the effects of shift work, it is important to establish a consistent sleep schedule, maintain a healthy diet and exercise regularly.
3. Travel: Jet lag is a common problem that occurs when travelling across multiple time zones. The body's internal clock becomes disrupted, leading to symptoms such as fatigue, insomnia, and digestive issues. To minimize the effects of jet lag, it is recommended to avoid tea, coffee and alcohol, order good quality nutritious food, and hydrate accordingly during the flight. Your circadian rhythm needs to re-synchronize in the new time zone, so exposure to morning sunlight/ daylight when you reach your destination is essential. It is better to get as much sunlight as you can and stay awake the first day till the usual bedtime in that time zone. If you need sleep during the day, it’s best to only make it for a maximum of 20 minutes. Taking Australian Bush Flower Essences proves beneficial for most people. Kinesiology balance can also help you to adjust to your new time zone.
4. Aging: As we age, the circadian rhythm can become less reliable, leading to sleep disturbances and insomnia. This is due to changes in the production of hormones, such as melatonin, which plays a crucial role in regulating the sleep-wake cycle. To maintain healthy sleep habits as you age, it is recommended to establish a consistent sleep schedule, avoid stimulants like caffeine, and limit exposure to bright light at night.
5. Genetics: The circadian rhythm is also influenced by genetics, as certain genes can affect the production and regulation of hormones that control sleep and wakefulness. Some people may naturally have a longer or shorter circadian cycle, which can lead to different sleep patterns and preferences. While genetics cannot be changed, they can be influenced by establishing healthy sleep habits by maintaining a consistent sleep schedule and avoiding disruptive habits like late-night screen time.
Importance of Hormones
Hormones cortisol and melatonin fluctuate during the day as part of your circadian rhythm. Cortisol helps regulate the sleep-wake cycle by promoting wakefulness during the day and inhibiting sleep at night. Cortisol levels are highest in the morning, which helps us wake up and stay alert during the day, and gradually decrease as the day progresses, preparing our bodies for sleep at night. Melatonin is released in response to darkness, which signals the brain to prepare for sleep. Melatonin levels remain high throughout the night, promoting deep and restful sleep. In the morning, as light levels increase, melatonin production decreases, signalling the body to wake up and start the day. Other hormones that play a role in alertness and circadian rhythm include vasopressin, acetylcholine, insulin and leptin.
Full Spectrum Light
Optimal light exposure is essential for your hormones and circadian rhythm function. If you spend most of your week indoors and your eyes and skin see more artificial light from screens, or a bulb or a window, than from natural light, you need to read on. Full-spectrum light is the strongest influence on your circadian rhythm. Natural, full-spectrum light impacts many different physiological and biochemical processes and is essential for optimal functioning as well as healing. Start by viewing natural bright light early in the morning, within 30 minutes of waking up. General guidelines to view light on a clear sunny day are about 10 minutes or longer, if it is cloudy, you will need about 20 minutes. Do not wear sunglasses when you viewing early morning light. Dr Samer Hattar, a Senior Investigator and Chief of the Section on Light and Circadian Rhythms from the National Institute of Mental Health confirms that additional natural sunlight exposure during the day and also afternoon and early evening has many additional benefits. Apart from optimising your inner clock you also protect your nervous system. Aim for at least 30 minutes of sunlight during the day and afternoon, with as much skin exposure as possible. The use of light in optimising skin health, appearance, longevity, wound healing, hormone balance, and regulating sleep, alertness, and mood and even for offsetting dementia has been used in medicine for over 100 years. Light has such a powerful effect on so many aspects of our biology, it can be translated into electrical signals in our brain and body, to hormone signals in our brain and body and also into cascades of biological pathways, meaning light can change the genes that the cells of your body express. In 1903, the Nobel Prize was given to Niels Ryberg Finsen from Denmark for the use of phototherapy for the successful treatment of lupus vulgaris, an autoimmune condition, which is usually labelled irreversible.
Our bodies are true masterpieces of nature, intricately designed to function in harmony with the environment around us. Whether we are ready to admit it or not the truth is that our health is largely in our own hands. Mastering the internal clock requires a conscious effort to establish healthy habits and routines that promote a healthy sleep-wake cycle. By following these tips and being mindful of the effects of lifestyle factors, you can achieve optimal cognitive and physical functioning and improve your overall wellbeing.
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