Our bodies are incredibly well designed and follow an intricate system of internal clocks. These internal clocks, known as circadian rhythms, govern multiple physiological processes, from our sleep-wake cycle to our metabolism and even organ function. In this article, we’ll break down what circadian rhythms are, why they are important, and offer practical steps to help optimise your body.
Think of it like an orchestra. The conductor of this orchestra is a master clock in your brain called the suprachiasmatic nucleus (SCN), and all the different clocks (circadian rhythms) in your body are like the musicians. Each of these circadian rhythms has its own role, controlling things like digestion, hormone levels, body temperature, and your sleep-wake cycle. But they all follow the same basic timing, directed by the master clock (the SCN), which is primarily influenced by light and darkness.
Whilst the main stimulus for the SCN is light, other stimulus such as temperature, physical activity and even food intake can affect the delicate balance of rhythms.
1. Get morning light first thing
If you can, go outside within an hour of waking up. If you cannot get outdoors, draw open the curtains or blinds and get as much light exposure as possible after waking and before you start your day.
2. Set a regular sleep schedule
Choose a realistic bedtime and wake-up time and stick to it, even on weekends when it may pain you to do so. Consistency is key!
3. Read for 10-15 minutes or listen to a relaxing audio meditation before you go to sleep.
Switch nighttime scrolling or TV in bed for 10-15 minutes of relaxation before you fall asleep to protect your melatonin and promote more deep and restful sleep.
The circadian rhythms affect every facet of our health and well-being, from sleep to mental clarity, mood, and hormones. By incorporating simple techniques like adjusting activity and meal timings around daylight hours can lead to better sleep, improved energy, and a more balanced emotional state.
What are Circadian rhythms?
All of us have internal clocks – also known as circadian rhythms; and nearly every tissue and organ have its own one. The term ‘circadian’ comes from two Latin words, ‘circa’ (approximate) and ‘dies’ (days) and the circadian rhythms refer to lots of physiological, behavioural and molecular changes (e.g. hormone release, sleep pattern and even body temperature) over roughly a 24 hr period.Think of it like an orchestra. The conductor of this orchestra is a master clock in your brain called the suprachiasmatic nucleus (SCN), and all the different clocks (circadian rhythms) in your body are like the musicians. Each of these circadian rhythms has its own role, controlling things like digestion, hormone levels, body temperature, and your sleep-wake cycle. But they all follow the same basic timing, directed by the master clock (the SCN), which is primarily influenced by light and darkness.
Whilst the main stimulus for the SCN is light, other stimulus such as temperature, physical activity and even food intake can affect the delicate balance of rhythms.
How Circadian Rhythms impact our health
Hormones like cortisol, melatonin and insulin are directly influenced by circadian rhythms.- Cortisol gets a bad reputation as ‘the stress hormone’ but is necessary for the body to regulate the immune system, energy levels and metabolism; along with creating a healthy stress response. It naturally peaks in the morning to help wake us up, and gradually declines during the day. Disruptions to cortisol can lead to numerous consequences such as fatigue, increased risk of illness, dysregulated blood sugar and weight gain and even mood disorders. Regulating circadian rhythms is key to keeping cortisol levels balanced.
- Melatonin is a hormone that acts as a powerful antioxidant, helping to protect cells from damage caused by free radicals. It is also involved into immune modulation, the regulation of reproductive hormones and plays a key role in sleep regulation. It is stimulated via darkness and peaks between 11pm and 5am, helping to induce restful sleep. Exposure to light at nighttime can result in the fall of melatonin, and can disrupt your menstrual cycles, ability to sleep well, ability to combat oxidative stress, and even mount an appropriate immune response.
- Insulin is a hormone responsible for getting glucose from the blood into the cells, to be utilised as energy. It also helps to balance blood sugar levels by transporting excess amounts of glucose (when levels are high) into the liver and muscles for storage. Insulin secretion and sensitivity varies throughout the day, with both decreasing naturally at nighttime. When this process is disturbed, it can lead to blood sugar dysregulation on waking, before you’ve even reached for anything to eat. This can have a knock-on effect on your weight, appetite, mood and even your energy levels. Glucose metabolism aka your blood sugar management, is kept in check via circadian control.
- Circadian rhythms also influence metabolism and digestion.
5 key tips for optimising circadian rhythms
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Expose yourself to natural light in the morning: One of the simplest ways to regulate your circadian rhythm is through exposure to natural light, especially in the morning. Light is the most powerful cue for resetting your body’s clock, helping you feel awake and alert during the day.
- Stick to a consistent sleep schedule: Going to bed and waking up at the same time every day (even on weekends), allows your body’s internal clock to remain in-sync. A consistent sleep-wake cycle will help to improve both your sleep quantity and quality.
- Limit blue light exposure at night: Blue light from screens (phones, computers, TVs) blocks the natural production of melatonin production. Switch off from screens and scrolling at least an hour before bed.
- Be mindful of meal timings: Keep consistent mealtimes to keep your metabolism supported. Aim to have the majority of food intake during daylight hours and avoid heavy meals late at night to avoid disrupting digestion and sleep.
- Wind down before bed: Establish a relaxing pre-bedtime routine such as reading, journalling, or even a bath with some candlelight, as this will help to signal to your brain that it’s soon time to sleep. By gradually reducing alertness and stress, your body can get into wind-down mode.
1. Get morning light first thing
If you can, go outside within an hour of waking up. If you cannot get outdoors, draw open the curtains or blinds and get as much light exposure as possible after waking and before you start your day.
2. Set a regular sleep schedule
Choose a realistic bedtime and wake-up time and stick to it, even on weekends when it may pain you to do so. Consistency is key!
3. Read for 10-15 minutes or listen to a relaxing audio meditation before you go to sleep.
Switch nighttime scrolling or TV in bed for 10-15 minutes of relaxation before you fall asleep to protect your melatonin and promote more deep and restful sleep.
The circadian rhythms affect every facet of our health and well-being, from sleep to mental clarity, mood, and hormones. By incorporating simple techniques like adjusting activity and meal timings around daylight hours can lead to better sleep, improved energy, and a more balanced emotional state.
Written by Cara Shaw, Registered Women's Health Nutritional Therapist
References
National Institute of General Medical Sciences https://nigms.nih.gov/education/fact-sheets/Pages/Circadian-Rhythms.aspx
Santhi, N. Lazer, A.S. McCabe, P.J. et. al. (2016). ‘Sex differences in the circadian regulation of sleep and waking cognition in humans’, PNAS USA, 113(9).
Serin, Y. Tek, N.A. (2019). ‘Effect of Circadian Rhythm on Metabolic Processes and the Regulation of Energy Balance’, Annals of Nutrition & Metabolism, 74(4), pp.322-330.
Tranah, G. J. Blackwell, T. Ancoli-Israel, S. et. al. (2010). ‘Circadian activity rhythms and mortality: the Study of Osteoporotic Fractures’, J Am Geriatr Soc. 58(2), pp. 282-291.
