Does Your Circadian Rhythm Need Resetting?
Are you experiencing any of these signs?
The human body is a complex network of cells operating on a myriad of internal clocks known as circadian rhythms. These rhythms govern everything from your sleep-wake cycles to hormone production, influencing health, performance and overall well-being.
As the sun rises and sets, the body dances to the rhythm of these internal timekeepers, carrying out different biological functions.
Learn how circadian rhythms work, why they’re vital for health and how they are influenced by diet, sleep and light.
What are circadian rhythms?
Circadian rhythms are the body’s internal clocks that regulate various physiological processes over a 24-hour cycle. Derived from the Latin words “circa” (around) and “diem” (day), these rhythms are deeply ingrained in our biology, ensuring our bodies are in sync with the natural cycles of light and darkness. While the most well-known circadian rhythm is the sleep-wake cycle, these rhythms extend to nearly every aspect of our physiology, including body temperature, hormone secretion, digestion and cognitive function.
How do circadian rhythms work?
At the heart of circadian rhythms is the body’s master clock, the suprachiasmatic nucleus (SCN), located in the brain’s hypothalamus. The SCN receives information about light exposure from the eyes, helping it align the body’s internal clocks with the external environment. As the sun rises, the SCN triggers the release of hormones like cortisol, signalling wakefulness and energy. Conversely, as the sun sets, melatonin production increases, inducing feelings of drowsiness and preparing the body for restorative sleep.
Factors that influence circadian rhythms
Irregular sleep patterns such as going to bed too late or having disrupted sleep due to sleep apnoea or a wakeful child can result in insufficient sleep and a misalignment of circadian rhythms.
Exposure to artificial light (especially from electronic devices) at night can confuse your internal clocks, disrupting your sleep-wake cycle and contribute to sleep disorders.
Jet lag, caused by rapid travel across time zones, leads to sleep disturbances and fatigue as the body’s internal clocks misalign with local time. Adaptation to the new time zone often takes a few 3 -4 days to adjust.
Shift work forces individuals to be awake when their bodies signal sleep, resulting in irregular sleep patterns which disrupts circadian rhythms.
Demanding schedules and constant connectivity can push you to deviate from the natural rhythm of your internal clocks.
Meal timing and irregular eating patterns, such as consuming meals at inconsistent times or eating late at night, can disrupt your body’s internal clocks.
Food choices – the types of foods you consume can also affect your circadian rhythms. A high-fat or high-sugar diet, particularly when consumed late at night, may disrupt your internal clocks and lead to sleep disruption.
How circadian rhythm disruptions affects health
Disruption to the natural alignment of your internal clock can potentially open the door to a host of health issues, including:
- Sleep disorders – insomnia, waking too early, poor sleep quality
- Fatigue and listlessness
- Decreased cognitive function – poor memory, less alert and focused
- Mood swings, irritability, depression and anxiety
- Metabolic disorders such as obesity and diabetes (poor glucose regulation)
- Weakened immune system and more susceptible to infections
- Cardiovascular problems – high blood pressure, arrythmias, heart risks
- Digestive issues – irregular bowel movements, reflux, bloating, heartburn
- Hormonal changes and less able to deal with stress
Circadian rhythm over a 24-hour day
Morning (approx. 6am – 9am)
- Cortisol awakening response: Cortisol typically surges shortly after waking up. This helps increase alertness and prepare the body for the day ahead.
- Body temperature: Body temperature begins to rise, promoting wakefulness and metabolic activity.
- Increased heart rate: Heart rate gradually increases, contributing to a sense of wakefulness.
- Melatonin decline: Melatonin (sleep hormone) decreases to its lowest levels in the morning.
Late morning (approx. 9am – 12pm)
- Peak alertness: Cognitive functions, alertness and concentration tend to peak during late morning hours.
- Digestive activity: Digestive processes become more active, optimising nutrient absorption from meals.
Afternoon (approx. 12pm – 3pm)
- Lunchtime: The body’s digestive system is in full swing, making it an ideal time for lunch.
- Post-lunch dip: Many people experience a slight drop in alertness, often referred to as the “afternoon slump.”
Early evening (approx. 5pm – 7pm)
- Temperature decline: Body temperature starts to drop, signalling the body to wind down in preparation for sleep.
- Dim light melatonin onset (DLMO): The pineal gland (in the brain) begins to release melatonin, preparing the body for sleep onset.
Late evening (approx. 9pm – 11pm)
- Melatonin release: Melatonin levels continue to rise, contributing to feelings of sleepiness.
- Sleep onset: Most people begin to feel drowsy and prepare for sleep during this time.
Night (approx. 11pm – 5am)
- Deep sleep: The first half of the night is characterised by deeper stages of sleep which are essential for physical and mental restoration.
- REM sleep: The second half of the night is marked by periods of Rapid Eye Movement (REM) sleep, associated with vivid dreams and cognitive consolidation.
- Body repair: Cellular repair and growth processes are active during sleep, supporting overall health.
- Temperature minimum: Body temperature reaches its lowest point in the early morning hours, contributing to a deep sleep state.
Early morning (approx. 5am – 6am)
- Pre-wakefulness: As the body prepares to wake up, cortisol levels start to rise again, aiding in the transition from sleep to wakefulness.
- Body temperature rises: Body temperature begins to increase, helping to promote wakefulness.
Healthy body clock habits
Being aware of your internal body clock and how it is influenced by factors like sleep patterns, light exposure, and meal timing can help you align your daily routines with your natural rhythms, potentially avoiding health complications associated with circadian rhythm disruptions. This alignment can enhance your sleep quality, mood, cognitive function, and overall well-being.
Keep an eye out for our next blog on how to optimise your circadian rhythm to promote healthy ageing, peak performance and cognitive function.
