Your Body’s Internal Clock: Why Circadian Rhythm Matters

Your Body’s Internal Clock:

Why Circadian Rhythm Matters

Written by: Clement Ng, Nutritionist of HealthPro | 6 minutes read

Circadian Rhythm

A circadian rhythm is your body’s built-in 24-hour internal clock that regulates various physiological processes, including the sleep-wake cycle, hormone release, metabolism, and body temperature (Victoria A. Acosta-Rodríguez, 2021).

Your body thrives on routine and functions optimally when its internal clock is aligned with the natural cycle of daylight and darkness (Tracey L. Sletten, 2022).

This alignment helps coordinate biological processes with the changing environment, allowing the body to anticipate daily demands rather than simply react to them (Tae Won Kim, 2015).

Insights of Circadian Rhythm

The circadian system is regulated by the suprachiasmatic nucleus (SCN), a region of the hypothalamus that acts as the body’s central clock (Cambria Glosz, 2023).

Light entering the eyes sends signals to the SCN, allowing it to synchronise the body’s internal timing with the external light-dark cycle (Victoria A. Acosta-Rodríguez, 2021).

The SCN then coordinates peripheral clocks found throughout the body, helping regulate daily biological processes (Victoria A. Acosta-Rodríguez, 2021).

These rhythms influence how you feel at different times of the day. Cortisol typically rises in the morning to support alertness and energy mobilisation, while melatonin levels rise in the evening to help prepare the body for sleep (Tae Won Kim, 2015).

Together, these changes help regulate the natural transition between wakefulness and rest (Victoria A. Acosta-Rodríguez, 2021).

Circadian Rhythm in Modern Life

In today’s fast-paced world, maintaining a healthy circadian rhythm can be challenging.

Long working hours, chronic stress, irregular meal times, late-night screen use, and insufficient sleep can disrupt the body’s natural daily rhythms (Victoria A. Acosta-Rodríguez, 2021).

Unlike natural daylight, artificial lighting allows us to remain active long after sunset.

Combined with round-the-clock access to food and demanding work schedules, this can blur the distinction between day and night, making it harder for the body to maintain a consistent sleep-wake cycle (Victoria A. Acosta-Rodríguez, 2021).

Stress can further complicate matters by keeping the body in a heightened state of alertness when it should be winding down for rest (Victoria A. Acosta-Rodríguez, 2021).

When these lifestyle factors persist, they can create a mismatch between the body’s internal clock and daily routines, potentially affecting sleep quality and other physiological processes (Tae Won Kim, 2015).

Health Implications of Circadian Rhythm

Sleep Quality

When your circadian rhythm is aligned with the natural light-dark cycle, your body follows a more consistent schedule, making it easier to fall asleep and wake up at the appropriate times (Tracey L. Sletten, 2022).

Conversely, misalignment between your internal clock and the external environment can disrupt the timing of hormone release and interfere with sleep (Tae Won Kim, 2015).

As a result, you may wake up feeling groggy and remain tired during the day, only to become unusually alert in the evening (April Benshosan, 2025).

Metabolic Health

Circadian rhythm influences insulin sensitivity and blood glucose regulation throughout the day (Tae Won Kim, 2015).

It also contributes to natural fluctuations in hunger and appetite, which may increase the tendency to crave food at night (Frank AJL Scheer, 2013).

Eating late at night, when glucose regulation may be less efficient, can impair glucose metabolism, particularly when such habits become routine. Over time, this may contribute to an increased risk of metabolic conditions (Cambria Glosz, 2023).

In addition, prolonged exposure to artificial light at night has been associated with circadian disruption and adverse metabolic outcomes (Cambria Glosz, 2023).

Research in older adults has linked nighttime light exposure to factors such as increased body weight, waist circumference, triglyceride levels, and cholesterol levels (Tae Won Kim, 2015).

Brain and Mental Health

Circadian rhythm helps coordinate sleep and biological processes involved in cognitive processing, memory, and mood regulation (Cambria Glosz, 2023).

During sleep, the brain engages in processes that help clear metabolic waste products, including beta-amyloid and tau proteins, which are associated with neurodegenerative diseases (Clinique La Prairie, 2025).

When circadian rhythm is disrupted, sleep quality and continuity may suffer, potentially interfering with these restorative processes. Over time, this may contribute to an increased risk of cognitive decline and neurodegeneration (Victoria A. Acosta-Rodríguez, 2021).

Circadian misalignment may also affect mental well-being, typically manifesting as irritability, brain fog, low motivation, and mood disturbances (Tracey L. Sletten, 2022).

Longevity

Circadian disruption may interfere with restorative processes including autophagy (Cambria Glosz, 2023).

Autophagy is a cellular recycling process through which the body breaks down and reuses damaged cellular components and unwanted materials, helping maintain cellular health and function (Cambria Glosz, 2023).

When cellular maintenance becomes less efficient, damaged components and senescent cells may accumulate. This can contribute to inflammaging, a state of chronic, low-grade inflammation associated with aging and age-related diseases (Clinique La Prairie, 2025).

Application

Research suggests that the circadian system remains responsive to environmental cues as we age. Consistent daily habits can therefore help reinforce healthy rhythms and improve alignment between the internal clock and the external environment (Clinique La Prairie, 2025).

a.     Establish a consistent sleep-wake cycle (April Benshosan, 2026)

Going to bed and waking up at approximately the same time every day helps reinforce your circadian rhythm, making it easier for your body to recognise when it is time to wind down and when it is time to wake up.

b.     Increase morning sunlight exposure (April Benshosan, 2021)

Exposure to bright natural daylight in the morning helps synchronise your circadian clock, reinforcing the daytime signal that prepares your body for daily activities.

c.     Limit nighttime exposure to artificial light (Cambria Glosz, 2023)

Dimming the lights at least one hour before bedtime can support the natural rise in melatonin levels and help prepare your body for sleep.

d.     Limit the use of electronic devices before sleep (Cambria Glosz, 2023)

Electronic devices emit blue light, the same type that is present in daylight which suppresses melatonin secretion and delays the body’s preparation for sleep.

e.     Keep your bedroom cool (April Benshosan, 2026)

Keeping your bedroom at a comfortably cool temperature can support the body’s natural cooling process and help you fall asleep more easily.

f.        Avoid late-night eating and stimulants (Ahrenholt, Karina, 2025)

Eating large meals close to bedtime may interfere with sleep and metabolic regulation.

Caffeine can delay sleep by promoting alertness, while alcohol may disrupt sleep quality and continuity.

g.      Exercise regularly at the right time (April Benshosan, 2025)

Regular physical activity can promote deep restorative sleep. However, intense exercise too close to bedtime may make it harder for some people to fall asleep, as it can temporarily elevate body temperature, heart rate, and alertness.

h.     Consider targeted supplementation

Stress, racing thoughts, and difficulty switching off after a hectic day can make it harder to unwind at bedtime.

Activa Well-Being Sleep combines various herbs that help promote relaxation, calm the nervous system, and support emotional balance.

It also contains L-tryptophan, a precursor to serotonin and melatonin. These compounds play important roles in mood regulation and the body’s natural sleep-wake cycle, complementing a holistic approach to supporting restful sleep.