Your Circadian Rhythm
The term ‘circadian rhythm’ refers to a natural, internal process that regulates the sleep-wake cycle and repeats roughly every 24 hours. Driven by an internal ‘biological clock’, its role is to help synchronise your body’s behaviours, physiology, and metabolic processes to the day-night cycle in your immediate environment.
The hypothalamus hosts the headquarters for the physiological governance of our circadian rhythm: the suprachiasmatic nucleus (SCN). As the brain’s ‘master clock’, the SCN receives direct input from the eyes through the retinohypothalamic tract. This allows the SCN to synchronise with the light-dark cycle of the environment, thus corresponding to our body’s day-night cycle alignment.
Circadian rhythms at the cellular level are driven by a feedback loop involving clock genes (namely, CLOCK, BMAL1, PER, and CRY.) These genes create proteins that accumulate in a rhythmic pattern over 24 hours. Once they reach a certain level, they inhibit their own production, creating a self-sustaining cycle.
The Role of Light
Light is the primary external cue (zeitgeber) that influences circadian rhythms. During the day, exposure to light signals the SCN to suppress melatonin, the hormone responsible for sleep. In darkness, the SCN triggers the pineal gland to release melatonin, promoting sleep.
It is integral that the SCN receives optimal light signals from the retina to regulate the circadian cycle at any given time of day. Inconsistent or excessive light exposure (e.g., artificial light at night) desynchronises the SCN from natural day-night cycles. This misalignment leads to circadian phase shifts, which can cause physiological systems to operate out of sync, ultimately leading to chronic health concerns.
The Impact of Circadian Disruption
How it all comes together – and why we harp on about the importance of your artificial light environment!
- Suppression of melatonin: Blue light (especially from screens) at night suppresses the release of melatonin, a hormone crucial for signalling sleep onset. Low melatonin levels disrupt sleep cycles, impairing critical restorative processes (i.e., cellular repair, immune function, and memory consolidation).
- Altered hormone regulation: Light disruption interferes with the secretion of key hormones, including:
- Cortisol: Normally peaks in the morning and declines at night, but irregular light exposure can delay or flatten this cycle.
- Insulin: Circadian misalignment alters insulin sensitivity, contributing to metabolic disorders.
- Immune and cellular effects: Light disruption can decrease night-time immune repair and increase inflammatory response throughout the body. Prolonged disruptions are associated with DNA damage and may increase the risk of cancer, particularly breast and prostate cancer.
- Mental health impacts: Abnormal light exposure disturbs circadian regulation of mood-related neurotransmitters like serotonin. Seasonal Affective Disorder (SAD) and other mood disorders are often linked to light disruption and circadian misalignment.
- Impaired Sleep-Wake Cycle: Prolonged light exposure at night shifts the body’s internal clock later, leading to Delayed Sleep Phase Syndrome (DSPS). Further, poor sleep quality and duration can result in cognitive impairment (e.g., memory loss, reduced alertness), and mood disturbances (e.g., anxiety, depression), among other psychological and emotional deficiencies.
Common Disruptions to Your Circadian Rhythm
- Blue light at night: Blue light from screens (i.e., smartphones, computers), can interfere with the production of melatonin, the hormone that promotes sleep. Exposure to bright light at night can result in disrupted sleep patterns, poor sleep quality, and difficulty waking up in the morning. Over time, this can lead to sleep deprivation, which can impair cognitive function, mood, and overall health.
- Caffeine and stimulants: Consuming caffeine or other stimulants (e.g., nicotine) too late in the day can interfere with the ability to fall asleep. This results in delayed sleep onset, poorer sleep quality, and reduced alertness the following day.
- Chronic stress: Prolonged stress or anxiety can affect the production of cortisol, which has a daily rhythm of its own. High cortisol levels late in the evening can make it harder to wind down for sleep. This results in difficulty falling asleep, sleep disturbances, and feeling fatigued during the day.
- Shift work: People who work at night or have rotating shifts experience a mismatch between their sleep-wake cycle and the natural day-night cycle. This places individuals at an increased risk of sleep disorders, fatigue, reduced alertness, and impaired cognitive performance.
Other common (but not always commonly known!) factors that can contribute to an impaired circadian rhythm include late night meals, alcohol consumption, and vigorous late afternoon/evening exercise.
Supporting Your Circadian Rhythm
- Sunlight in the morning: Exposure to natural sunlight helps reset your biological clock and promotes alertness during the day. Aim for 15-30 minutes of sunlight within the first few hours of waking.
- Consistent sleep schedule: Where possible try to go to bed and wake up at the same time every day to help reinforce your body’s natural rhythm.
- Limit blue light exposure in the evenings (aka put those phones away!): Avoid screens for at least an hour before bed. Alternatively, use blue light filters on devices if you must use them.
- Create a relaxing bed-time routine: Develop a calming pre-sleep routine, such as reading a book, taking a warm bath, or doing light stretching or meditation to help signal to your body that it’s time to sleep.
How Naturopathy Can Help
Revital Health has a team of highly skilled degree-qualified practitioners who are able to support you to nourish your circadian rhythm in a variety of ways, including:
Herbal Medicine
Herbal medicine can be a gentle and natural way to support your body’s circadian rhythm. Many herbs have a rich scientific profile supporting their calming and sedative properties which can help regulate sleep cycles, reduce anxiety, and support relaxation in the evening. These include – but are not limited to – chamomile, lavender, California poppy, and passionflower.
Bespoke Tea Blends
Herbal tea consumed in the evening can promote relaxation and prepare the body for restful sleep. Revital Health has our very own chief herbal tea blender (Kris Walker) who creates customised blends specific to an individual’s needs. We also have an ‘Aurora’ tea blend filled with herbs that nourish the central nervous system available to purchase on our website!
To find out more about how naturopathy can help get your circadian rhythm back on track, book a free 10-minute discovery call with one of our practitioners today!
